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diff --git a/Doc/api.tex b/Doc/api.tex index ef93b62..f36f105 100644 --- a/Doc/api.tex +++ b/Doc/api.tex @@ -17,9 +17,9 @@ \begin{abstract} \noindent -This manual documents the API used by \C{} (or \Cpp{}) programmers who want -to write extension modules or embed Python. It is a companion to -``Extending and Embedding the Python Interpreter'', which describes +This manual documents the API used by \C{} (or \Cpp{}) programmers who +want to write extension modules or embed Python. It is a companion to +\emph{Extending and Embedding the Python Interpreter}, which describes the general principles of extension writing but does not document the API functions in detail. @@ -41,12 +41,12 @@ The Application Programmer's Interface to Python gives \C{} and \Cpp{} programmers access to the Python interpreter at a variety of levels. The API is equally usable from \Cpp{}, but for brevity it is generally referred to as the Python/\C{} API. There are two fundamentally -different reasons for using the Python/\C{} API. The first reason is to -write ``extension modules'' for specific purposes; these are \C{} modules -that extend the Python interpreter. This is probably the most common -use. The second reason is to use Python as a component in a larger -application; this technique is generally referred to as ``embedding'' -Python in an application. +different reasons for using the Python/\C{} API. The first reason is +to write \emph{extension modules} for specific purposes; these are +\C{} modules that extend the Python interpreter. This is probably the +most common use. The second reason is to use Python as a component in +a larger application; this technique is generally referred to as +\dfn{embedding} Python in an application. Writing an extension module is a relatively well-understood process, where a ``cookbook'' approach works well. There are several tools @@ -55,7 +55,7 @@ Python in other applications since its early existence, the process of embedding Python is less straightforward that writing an extension. Python 1.5 introduces a number of new API functions as well as some changes to the build process that make embedding much simpler. -This manual describes the 1.5 state of affair. +This manual describes the \version\ state of affair. % XXX Eventually, take the historical notes out Many API functions are useful independent of whether you're embedding @@ -69,26 +69,30 @@ attempting to embed Python in a real application. All function, type and macro definitions needed to use the Python/C API are included in your code by the following line: -\code{\#include "Python.h"} +\begin{verbatim} +#include "Python.h" +\end{verbatim} -This implies inclusion of the following standard header files: -stdio.h, string.h, errno.h, and stdlib.h (if available). +This implies inclusion of the following standard headers: +\code{<stdio.h>}, \code{<string.h>}, \code{<errno.h>}, and +\code{<stdlib.h>} (if available). All user visible names defined by Python.h (except those defined by -the included standard headers) have one of the prefixes \code{Py} or -\code{_Py}. Names beginning with \code{_Py} are for internal use +the included standard headers) have one of the prefixes \samp{Py} or +\samp{_Py}. Names beginning with \samp{_Py} are for internal use only. Structure member names do not have a reserved prefix. -Important: user code should never define names that begin with -\code{Py} or \code{_Py}. This confuses the reader, and jeopardizes -the portability of the user code to future Python versions, which may -define additional names beginning with one of these prefixes. +\strong{Important:} user code should never define names that begin +with \samp{Py} or \samp{_Py}. This confuses the reader, and +jeopardizes the portability of the user code to future Python +versions, which may define additional names beginning with one of +these prefixes. \section{Objects, Types and Reference Counts} Most Python/C API functions have one or more arguments as well as a return value of type \code{PyObject *}. This type is a pointer -(obviously!) to an opaque data type representing an arbitrary Python +to an opaque data type representing an arbitrary Python object. Since all Python object types are treated the same way by the Python language in most situations (e.g., assignments, scope rules, and argument passing), it is only fitting that they should be @@ -97,13 +101,13 @@ you never declare an automatic or static variable of type \code{PyObject}, only pointer variables of type \code{PyObject *} can be declared. -All Python objects (even Python integers) have a ``type'' and a -``reference count''. An object's type determines what kind of object +All Python objects (even Python integers) have a \dfn{type} and a +\dfn{reference count}. An object's type determines what kind of object it is (e.g., an integer, a list, or a user-defined function; there are -many more as explained in the Python Language Reference Manual). For +many more as explained in the \emph{Python Reference Manual}). For each of the well-known types there is a macro to check whether an -object is of that type; for instance, \code{PyList_Check(a)} is true -iff the object pointed to by \code{a} is a Python list. +object is of that type; for instance, \samp{PyList_Check(\var{a})} is +true iff the object pointed to by \var{a} is a Python list. \subsection{Reference Counts} @@ -120,8 +124,8 @@ with objects that reference each other here; for now, the solution is ``don't do that''.) Reference counts are always manipulated explicitly. The normal way is -to use the macro \code{Py_INCREF(a)} to increment an object's -reference count by one, and \code{Py_DECREF(a)} to decrement it by +to use the macro \cfunction{Py_INCREF()} to increment an object's +reference count by one, and \cfunction{Py_DECREF()} to decrement it by one. The decref macro is considerably more complex than the incref one, since it must check whether the reference count becomes zero and then cause the object's deallocator, which is a function pointer contained @@ -136,7 +140,7 @@ increment is a simple operation. It is not necessary to increment an object's reference count for every local variable that contains a pointer to an object. In theory, the -oject's reference count goes up by one when the variable is made to +object's reference count goes up by one when the variable is made to point to it and it goes down by one when the variable goes out of scope. However, these two cancel each other out, so at the end the reference count hasn't changed. The only real reason to use the @@ -149,21 +153,21 @@ that are passed as arguments to \C{} functions in an extension module that are called from Python; the call mechanism guarantees to hold a reference to every argument for the duration of the call. -However, a common pitfall is to extract an object from a list and -holding on to it for a while without incrementing its reference count. -Some other operation might conceivably remove the object from the -list, decrementing its reference count and possible deallocating it. -The real danger is that innocent-looking operations may invoke -arbitrary Python code which could do this; there is a code path which -allows control to flow back to the user from a \code{Py_DECREF()}, so -almost any operation is potentially dangerous. +However, a common pitfall is to extract an object from a list and +hold on to it for a while without incrementing its reference count. +Some other operation might conceivably remove the object from the +list, decrementing its reference count and possible deallocating it. +The real danger is that innocent-looking operations may invoke +arbitrary Python code which could do this; there is a code path which +allows control to flow back to the user from a \cfunction{Py_DECREF()}, +so almost any operation is potentially dangerous. A safe approach is to always use the generic operations (functions -whose name begins with \code{PyObject_}, \code{PyNumber_}, -\code{PySequence_} or \code{PyMapping_}). These operations always +whose name begins with \samp{PyObject_}, \samp{PyNumber_}, +\samp{PySequence_} or \samp{PyMapping_}). These operations always increment the reference count of the object they return. This leaves -the caller with the responsibility to call \code{Py_DECREF()} when -they are done with the result; this soon becomes second nature. +the caller with the responsibility to call \cfunction{Py_DECREF()} +when they are done with the result; this soon becomes second nature. \subsubsection{Reference Count Details} @@ -171,24 +175,24 @@ The reference count behavior of functions in the Python/C API is best expelained in terms of \emph{ownership of references}. Note that we talk of owning references, never of owning objects; objects are always shared! When a function owns a reference, it has to dispose of it -properly -- either by passing ownership on (usually to its caller) or -by calling \code{Py_DECREF()} or \code{Py_XDECREF()}. When a function -passes ownership of a reference on to its caller, the caller is said -to receive a \emph{new} reference. When no ownership is transferred, -the caller is said to \emph{borrow} the reference. Nothing needs to -be done for a borrowed reference. +properly --- either by passing ownership on (usually to its caller) or +by calling \cfunction{Py_DECREF()} or \cfunction{Py_XDECREF()}. When +a function passes ownership of a reference on to its caller, the +caller is said to receive a \emph{new} reference. When no ownership +is transferred, the caller is said to \emph{borrow} the reference. +Nothing needs to be done for a borrowed reference. Conversely, when calling a function passes it a reference to an object, there are two possibilities: the function \emph{steals} a reference to the object, or it does not. Few functions steal -references; the two notable exceptions are \code{PyList_SetItem()} and -\code{PyTuple_SetItem()}, which steal a reference to the item (but not to -the tuple or list into which the item it put!). These functions were -designed to steal a reference because of a common idiom for populating -a tuple or list with newly created objects; for example, the code to -create the tuple \code{(1, 2, "three")} could look like this -(forgetting about error handling for the moment; a better way to code -this is shown below anyway): +references; the two notable exceptions are +\cfunction{PyList_SetItem()} and \cfunction{PyTuple_SetItem()}, which +steal a reference to the item (but not to the tuple or list into which +the item it put!). These functions were designed to steal a reference +because of a common idiom for populating a tuple or list with newly +created objects; for example, the code to create the tuple \code{(1, +2, "three")} could look like this (forgetting about error handling for +the moment; a better way to code this is shown below anyway): \begin{verbatim} PyObject *t; @@ -198,16 +202,17 @@ PyTuple_SetItem(t, 1, PyInt_FromLong(2L)); PyTuple_SetItem(t, 2, PyString_FromString("three")); \end{verbatim} -Incidentally, \code{PyTuple_SetItem()} is the \emph{only} way to set -tuple items; \code{PySequence_SetItem()} and \code{PyObject_SetItem()} -refuse to do this since tuples are an immutable data type. You should -only use \code{PyTuple_SetItem()} for tuples that you are creating +Incidentally, \cfunction{PyTuple_SetItem()} is the \emph{only} way to +set tuple items; \cfunction{PySequence_SetItem()} and +\cfunction{PyObject_SetItem()} refuse to do this since tuples are an +immutable data type. You should only use +\cfunction{PyTuple_SetItem()} for tuples that you are creating yourself. Equivalent code for populating a list can be written using -\code{PyList_New()} and \code{PyList_SetItem()}. Such code can also -use \code{PySequence_SetItem()}; this illustrates the difference -between the two (the extra \code{Py_DECREF()} calls): +\cfunction{PyList_New()} and \cfunction{PyList_SetItem()}. Such code +can also use \cfunction{PySequence_SetItem()}; this illustrates the +difference between the two (the extra \cfunction{Py_DECREF()} calls): \begin{verbatim} PyObject *l, *x; @@ -223,10 +228,10 @@ PySequence_SetItem(l, 2, x); Py_DECREF(x); You might find it strange that the ``recommended'' approach takes more code. However, in practice, you will rarely use these ways of creating and populating a tuple or list. There's a generic function, -\code{Py_BuildValue()}, that can create most common objects from \C{} -values, directed by a ``format string''. For example, the above two -blocks of code could be replaced by the following (which also takes -care of the error checking!): +\cfunction{Py_BuildValue()}, that can create most common objects from +\C{} values, directed by a \dfn{format string}. For example, the +above two blocks of code could be replaced by the following (which +also takes care of the error checking): \begin{verbatim} PyObject *t, *l; @@ -234,13 +239,14 @@ t = Py_BuildValue("(iis)", 1, 2, "three"); l = Py_BuildValue("[iis]", 1, 2, "three"); \end{verbatim} -It is much more common to use \code{PyObject_SetItem()} and friends -with items whose references you are only borrowing, like arguments -that were passed in to the function you are writing. In that case, -their behaviour regarding reference counts is much saner, since you -don't have to increment a reference count so you can give a reference -away (``have it be stolen''). For example, this function sets all -items of a list (actually, any mutable sequence) to a given item: +It is much more common to use \cfunction{PyObject_SetItem()} and +friends with items whose references you are only borrowing, like +arguments that were passed in to the function you are writing. In +that case, their behaviour regarding reference counts is much saner, +since you don't have to increment a reference count so you can give a +reference away (``have it be stolen''). For example, this function +sets all items of a list (actually, any mutable sequence) to a given +item: \begin{verbatim} int set_all(PyObject *target, PyObject *item) @@ -263,23 +269,25 @@ ownership responsibilities for that reference, many functions that return a referece to an object give you ownership of the reference. The reason is simple: in many cases, the returned object is created on the fly, and the reference you get is the only reference to the -object! Therefore, the generic functions that return object -references, like \code{PyObject_GetItem()} and -\code{PySequence_GetItem()}, always return a new reference (i.e., the -caller becomes the owner of the reference). +object. Therefore, the generic functions that return object +references, like \cfunction{PyObject_GetItem()} and +\cfunction{PySequence_GetItem()}, always return a new reference (i.e., +the caller becomes the owner of the reference). It is important to realize that whether you own a reference returned -by a function depends on which function you call only -- \emph{the -plumage} (i.e., the type of the type of the object passed as an -argument to the function) \emph{don't enter into it!} Thus, if you -extract an item from a list using \code{PyList_GetItem()}, you don't -own the reference -- but if you obtain the same item from the same -list using \code{PySequence_GetItem()} (which happens to take exactly -the same arguments), you do own a reference to the returned object. - -Here is an example of how you could write a function that computes the +by a function depends on which function you call only --- \emph{the +plumage} (i.e., the type of the type of the object passed as an +argument to the function) \emph{doesn't enter into it!} Thus, if you +extract an item from a list using \cfunction{PyList_GetItem()}, you +don't own the reference --- but if you obtain the same item from the +same list using \cfunction{PySequence_GetItem()} (which happens to +take exactly the same arguments), you do own a reference to the +returned object. + +Here is an example of how you could write a function that computes the sum of the items in a list of integers; once using -\code{PyList_GetItem()}, once using \code{PySequence_GetItem()}. +\cfunction{PyList_GetItem()}, once using +\cfunction{PySequence_GetItem()}. \begin{verbatim} long sum_list(PyObject *list) @@ -342,36 +350,37 @@ All functions in the Python/C API can raise exceptions, unless an explicit claim is made otherwise in a function's documentation. In general, when a function encounters an error, it sets an exception, discards any object references that it owns, and returns an -error indicator -- usually \NULL{} or \code{-1}. A few functions +error indicator --- usually \NULL{} or \code{-1}. A few functions return a Boolean true/false result, with false indicating an error. Very few functions return no explicit error indicator or have an ambiguous return value, and require explicit testing for errors with -\code{PyErr_Occurred()}. +\cfunction{PyErr_Occurred()}. Exception state is maintained in per-thread storage (this is equivalent to using global storage in an unthreaded application). A -thread can be on one of two states: an exception has occurred, or not. -The function \code{PyErr_Occurred()} can be used to check for this: it -returns a borrowed reference to the exception type object when an -exception has occurred, and \NULL{} otherwise. There are a number -of functions to set the exception state: \code{PyErr_SetString()} is -the most common (though not the most general) function to set the -exception state, and \code{PyErr_Clear()} clears the exception state. +thread can be on one of two states: an exception has occurred, or not. +The function \cfunction{PyErr_Occurred()} can be used to check for +this: it returns a borrowed reference to the exception type object +when an exception has occurred, and \NULL{} otherwise. There are a +number of functions to set the exception state: +\cfunction{PyErr_SetString()} is the most common (though not the most +general) function to set the exception state, and +\cfunction{PyErr_Clear()} clears the exception state. The full exception state consists of three objects (all of which can -be \NULL{} ): the exception type, the corresponding exception +be \NULL{}): the exception type, the corresponding exception value, and the traceback. These have the same meanings as the Python object \code{sys.exc_type}, \code{sys.exc_value}, \code{sys.exc_traceback}; however, they are not the same: the Python objects represent the last exception being handled by a Python -\code{try...except} statement, while the \C{} level exception state only -exists while an exception is being passed on between \C{} functions until -it reaches the Python interpreter, which takes care of transferring it -to \code{sys.exc_type} and friends. +\keyword{try} \ldots\ \keyword{except} statement, while the \C{} level +exception state only exists while an exception is being passed on +between \C{} functions until it reaches the Python interpreter, which +takes care of transferring it to \code{sys.exc_type} and friends. (Note that starting with Python 1.5, the preferred, thread-safe way to access the exception state from Python code is to call the function -\code{sys.exc_info()}, which returns the per-thread exception state +\function{sys.exc_info()}, which returns the per-thread exception state for Python code. Also, the semantics of both ways to access the exception state have changed so that a function which catches an exception will save and restore its thread's exception state so as to @@ -384,17 +393,17 @@ stack frames in the traceback.) As a general principle, a function that calls another function to perform some task should check whether the called function raised an exception, and if so, pass the exception state on to its caller. It -should discards any object references that it owns, and returns an -error indicator, but it should \emph{not} set another exception -- -that would overwrite the exception that was just raised, and lose -important reason about the exact cause of the error. +should discard any object references that it owns, and returns an +error indicator, but it should \emph{not} set another exception --- +that would overwrite the exception that was just raised, and lose +important information about the exact cause of the error. A simple example of detecting exceptions and passing them on is shown -in the \code{sum_sequence()} example above. It so happens that that -example doesn't need to clean up any owned references when it detects -an error. The following example function shows some error cleanup. -First, to remind you why you like Python, we show the equivalent -Python code: +in the \cfunction{sum_sequence()} example above. It so happens that +that example doesn't need to clean up any owned references when it +detects an error. The following example function shows some error +cleanup. First, to remind you why you like Python, we show the +equivalent Python code: \begin{verbatim} def incr_item(dict, key): @@ -448,15 +457,16 @@ int incr_item(PyObject *dict, PyObject *key) \end{verbatim} This example represents an endorsed use of the \code{goto} statement -in \C{}! It illustrates the use of \code{PyErr_ExceptionMatches()} and -\code{PyErr_Clear()} to handle specific exceptions, and the use of -\code{Py_XDECREF()} to dispose of owned references that may be -\NULL{} (note the `X' in the name; \code{Py_DECREF()} would crash -when confronted with a \NULL{} reference). It is important that -the variables used to hold owned references are initialized to -\NULL{} for this to work; likewise, the proposed return value is -initialized to \code{-1} (failure) and only set to success after -the final call made is successful. +in \C{}! It illustrates the use of +\cfunction{PyErr_ExceptionMatches()} and \cfunction{PyErr_Clear()} to +handle specific exceptions, and the use of \cfunction{Py_XDECREF()} to +dispose of owned references that may be \NULL{} (note the \samp{X} in +the name; \cfunction{Py_DECREF()} would crash when confronted with a +\NULL{} reference). It is important that the variables used to hold +owned references are initialized to \NULL{} for this to work; +likewise, the proposed return value is initialized to \code{-1} +(failure) and only set to success after the final call made is +successful. \section{Embedding Python} @@ -467,53 +477,54 @@ initialization, and possibly the finalization, of the Python interpreter. Most functionality of the interpreter can only be used after the interpreter has been initialized. -The basic initialization function is \code{Py_Initialize()}. This -initializes the table of loaded modules, and creates the fundamental -modules \code{__builtin__}, \code{__main__} and \code{sys}. It also -initializes the module search path (\code{sys.path}). +The basic initialization function is \cfunction{Py_Initialize()}. +This initializes the table of loaded modules, and creates the +fundamental modules \module{__builtin__}, \module{__main__} and +\module{sys}. It also initializes the module search path +(\code{sys.path}). -\code{Py_Initialize()} does not set the ``script argument list'' +\cfunction{Py_Initialize()} does not set the ``script argument list'' (\code{sys.argv}). If this variable is needed by Python code that will be executed later, it must be set explicitly with a call to \code{PySys_SetArgv(\var{argc}, \var{argv})} subsequent to the call -to \code{Py_Initialize()}. +to \cfunction{Py_Initialize()}. On most systems (in particular, on \UNIX{} and Windows, although the -details are slightly different), \code{Py_Initialize()} calculates the -module search path based upon its best guess for the location of the -standard Python interpreter executable, assuming that the Python -library is found in a fixed location relative to the Python +details are slightly different), \cfunction{Py_Initialize()} +calculates the module search path based upon its best guess for the +location of the standard Python interpreter executable, assuming that +the Python library is found in a fixed location relative to the Python interpreter executable. In particular, it looks for a directory named -\code{lib/python1.5} (replacing \code{1.5} with the current +\file{lib/python\version} (replacing \file{\version} with the current interpreter version) relative to the parent directory where the -executable named \code{python} is found on the shell command search +executable named \file{python} is found on the shell command search path (the environment variable \code{\$PATH}). For instance, if the Python executable is found in -\code{/usr/local/bin/python}, it will assume that the libraries are in -\code{/usr/local/lib/python1.5}. (In fact, this particular path is -also the ``fallback'' location, used when no executable file named -\code{python} is found along \code{\$PATH}.) The user can override +\file{/usr/local/bin/python}, it will assume that the libraries are in +\file{/usr/local/lib/python\version}. (In fact, this particular path +is also the ``fallback'' location, used when no executable file named +\file{python} is found along \code{\$PATH}.) The user can override this behavior by setting the environment variable \code{\$PYTHONHOME}, or insert additional directories in front of the standard path by setting \code{\$PYTHONPATH}. The embedding application can steer the search by calling \code{Py_SetProgramName(\var{file})} \emph{before} calling -\code{Py_Initialize()}. Note that \code{\$PYTHONHOME} still overrides -this and \code{\$PYTHONPATH} is still inserted in front of the -standard path. An application that requires total control has to -provide its own implementation of \code{Py_GetPath()}, -\code{Py_GetPrefix()}, \code{Py_GetExecPrefix()}, -\code{Py_GetProgramFullPath()} (all defined in +\cfunction{Py_Initialize()}. Note that \code{\$PYTHONHOME} still +overrides this and \code{\$PYTHONPATH} is still inserted in front of +the standard path. An application that requires total control has to +provide its own implementation of \cfunction{Py_GetPath()}, +\cfunction{Py_GetPrefix()}, \cfunction{Py_GetExecPrefix()}, +\cfunction{Py_GetProgramFullPath()} (all defined in \file{Modules/getpath.c}). Sometimes, it is desirable to ``uninitialize'' Python. For instance, the application may want to start over (make another call to -\code{Py_Initialize()}) or the application is simply done with its +\cfunction{Py_Initialize()}) or the application is simply done with its use of Python and wants to free all memory allocated by Python. This -can be accomplished by calling \code{Py_Finalize()}. The function -\code{Py_IsInitialized()} returns true iff Python is currently in the +can be accomplished by calling \cfunction{Py_Finalize()}. The function +\cfunction{Py_IsInitialized()} returns true iff Python is currently in the initialized state. More information about these functions is given in a later chapter. @@ -563,42 +574,44 @@ of Python objects. \begin{cfuncdesc}{void}{Py_INCREF}{PyObject *o} Increment the reference count for object \code{o}. The object must not be \NULL{}; if you aren't sure that it isn't \NULL{}, use -\code{Py_XINCREF()}. +\cfunction{Py_XINCREF()}. \end{cfuncdesc} \begin{cfuncdesc}{void}{Py_XINCREF}{PyObject *o} -Increment the reference count for object \code{o}. The object may be +Increment the reference count for object \var{o}. The object may be \NULL{}, in which case the macro has no effect. \end{cfuncdesc} \begin{cfuncdesc}{void}{Py_DECREF}{PyObject *o} -Decrement the reference count for object \code{o}. The object must +Decrement the reference count for object \var{o}. The object must not be \NULL{}; if you aren't sure that it isn't \NULL{}, use -\code{Py_XDECREF()}. If the reference count reaches zero, the object's -type's deallocation function (which must not be \NULL{}) is invoked. +\cfunction{Py_XDECREF()}. If the reference count reaches zero, the +object's type's deallocation function (which must not be \NULL{}) is +invoked. \strong{Warning:} The deallocation function can cause arbitrary Python -code to be invoked (e.g. when a class instance with a \code{__del__()} +code to be invoked (e.g. when a class instance with a \method{__del__()} method is deallocated). While exceptions in such code are not propagated, the executed code has free access to all Python global variables. This means that any object that is reachable from a global -variable should be in a consistent state before \code{Py_DECREF()} is +variable should be in a consistent state before \cfunction{Py_DECREF()} is invoked. For example, code to delete an object from a list should copy a reference to the deleted object in a temporary variable, update -the list data structure, and then call \code{Py_DECREF()} for the +the list data structure, and then call \cfunction{Py_DECREF()} for the temporary variable. \end{cfuncdesc} \begin{cfuncdesc}{void}{Py_XDECREF}{PyObject *o} -Decrement the reference count for object \code{o}.The object may be -\NULL{}, in which case the macro has no effect; otherwise the -effect is the same as for \code{Py_DECREF()}, and the same warning +Decrement the reference count for object \var{o}. The object may be +\NULL{}, in which case the macro has no effect; otherwise the effect +is the same as for \cfunction{Py_DECREF()}, and the same warning applies. \end{cfuncdesc} The following functions or macros are only for internal use: -\code{_Py_Dealloc}, \code{_Py_ForgetReference}, \code{_Py_NewReference}, -as well as the global variable \code{_Py_RefTotal}. +\cfunction{_Py_Dealloc()}, \cfunction{_Py_ForgetReference()}, +\cfunction{_Py_NewReference()}, as well as the global variable +\code{_Py_RefTotal}. XXX Should mention Py_Malloc(), Py_Realloc(), Py_Free(), PyMem_Malloc(), PyMem_Realloc(), PyMem_Free(), PyMem_NEW(), @@ -614,11 +627,11 @@ Python exception handling. It works somewhat like the \UNIX{} last error that occurred. Most functions don't clear this on success, but will set it to indicate the cause of the error on failure. Most functions also return an error indicator, usually \NULL{} if they are -supposed to return a pointer, or -1 if they return an integer -(exception: the \code{PyArg_Parse*()} functions return 1 for success and -0 for failure). When a function must fail because some function it -called failed, it generally doesn't set the error indicator; the -function it called already set it. +supposed to return a pointer, or \code{-1} if they return an integer +(exception: the \code{PyArg_Parse*()} functions return \code{1} for +success and \code{0} for failure). When a function must fail because +some function it called failed, it generally doesn't set the error +indicator; the function it called already set it. The error indicator consists of three Python objects corresponding to the Python variables \code{sys.exc_type}, \code{sys.exc_value} and @@ -637,18 +650,19 @@ indicator. Call this function only when the error indicator is set. \begin{cfuncdesc}{PyObject *}{PyErr_Occurred}{} Test whether the error indicator is set. If set, return the exception -\code{type} (the first argument to the last call to one of the -\code{PyErr_Set*()} functions or to \code{PyErr_Restore()}). If not -set, return \NULL{}. You do not own a reference to the return value, -so you do not need to \code{Py_DECREF()} it. Note: do not compare the -return value to a specific exception; use -\code{PyErr_ExceptionMatches} instead, shown below. +\emph{type} (the first argument to the last call to one of the +\code{PyErr_Set*()} functions or to \cfunction{PyErr_Restore()}). If +not set, return \NULL{}. You do not own a reference to the return +value, so you do not need to \cfunction{Py_DECREF()} it. +\strong{Note:} do not compare the return value to a specific +exception; use \cfunction{PyErr_ExceptionMatches()} instead, shown +below. \end{cfuncdesc} \begin{cfuncdesc}{int}{PyErr_ExceptionMatches}{PyObject *exc} \strong{(NEW in 1.5a4!)} Equivalent to -\code{PyErr_GivenExceptionMatches(PyErr_Occurred(), \var{exc})}. +\samp{PyErr_GivenExceptionMatches(PyErr_Occurred(), \var{exc})}. This should only be called when an exception is actually set. \end{cfuncdesc} @@ -665,10 +679,11 @@ set. \begin{cfuncdesc}{void}{PyErr_NormalizeException}{PyObject**exc, PyObject**val, PyObject**tb} \strong{(NEW in 1.5a4!)} Under certain circumstances, the values returned by -\code{PyErr_Fetch()} below can be ``unnormalized'', meaning that -\var{*exc} is a class object but \var{*val} is not an instance of the -same class. This function can be used to instantiate the class in -that case. If the values are already normalized, nothing happens. +\cfunction{PyErr_Fetch()} below can be ``unnormalized'', meaning that +\code{*\var{exc}} is a class object but \code{*\var{val}} is not an +instance of the same class. This function can be used to instantiate +the class in that case. If the values are already normalized, nothing +happens. \end{cfuncdesc} \begin{cfuncdesc}{void}{PyErr_Clear}{} @@ -711,25 +726,25 @@ message; it is converted to a string object. \end{cfuncdesc} \begin{cfuncdesc}{void}{PyErr_SetObject}{PyObject *type, PyObject *value} -This function is similar to \code{PyErr_SetString()} but lets you +This function is similar to \cfunction{PyErr_SetString()} but lets you specify an arbitrary Python object for the ``value'' of the exception. You need not increment its reference count. \end{cfuncdesc} \begin{cfuncdesc}{void}{PyErr_SetNone}{PyObject *type} -This is a shorthand for \code{PyErr_SetString(\var{type}, Py_None}. +This is a shorthand for \samp{PyErr_SetObject(\var{type}, Py_None)}. \end{cfuncdesc} \begin{cfuncdesc}{int}{PyErr_BadArgument}{} -This is a shorthand for \code{PyErr_SetString(PyExc_TypeError, +This is a shorthand for \samp{PyErr_SetString(PyExc_TypeError, \var{message})}, where \var{message} indicates that a built-in operation was invoked with an illegal argument. It is mostly for internal use. \end{cfuncdesc} \begin{cfuncdesc}{PyObject *}{PyErr_NoMemory}{} -This is a shorthand for \code{PyErr_SetNone(PyExc_MemoryError)}; it +This is a shorthand for \samp{PyErr_SetNone(PyExc_MemoryError)}; it returns \NULL{} so an object allocation function can write -\code{return PyErr_NoMemory();} when it runs out of memory. +\samp{return PyErr_NoMemory();} when it runs out of memory. \end{cfuncdesc} \begin{cfuncdesc}{PyObject *}{PyErr_SetFromErrno}{PyObject *type} @@ -737,17 +752,18 @@ This is a convenience function to raise an exception when a \C{} library function has returned an error and set the \C{} variable \code{errno}. It constructs a tuple object whose first item is the integer \code{errno} value and whose second item is the corresponding error -message (gotten from \code{strerror()}), and then calls -\code{PyErr_SetObject(\var{type}, \var{object})}. On \UNIX{}, when -the \code{errno} value is \code{EINTR}, indicating an interrupted -system call, this calls \code{PyErr_CheckSignals()}, and if that set +message (gotten from \cfunction{strerror()}), and then calls +\samp{PyErr_SetObject(\var{type}, \var{object})}. On \UNIX{}, when +the \code{errno} value is \constant{EINTR}, indicating an interrupted +system call, this calls \cfunction{PyErr_CheckSignals()}, and if that set the error indicator, leaves it set to that. The function always returns \NULL{}, so a wrapper function around a system call can write -\code{return PyErr_NoMemory();} when the system call returns an error. +\samp{return PyErr_SetFromErrno();} when the system call returns an +error. \end{cfuncdesc} \begin{cfuncdesc}{void}{PyErr_BadInternalCall}{} -This is a shorthand for \code{PyErr_SetString(PyExc_TypeError, +This is a shorthand for \samp{PyErr_SetString(PyExc_TypeError, \var{message})}, where \var{message} indicates that an internal operation (e.g. a Python/C API function) was invoked with an illegal argument. It is mostly for internal use. @@ -756,20 +772,20 @@ argument. It is mostly for internal use. \begin{cfuncdesc}{int}{PyErr_CheckSignals}{} This function interacts with Python's signal handling. It checks whether a signal has been sent to the processes and if so, invokes the -corresponding signal handler. If the \code{signal} module is +corresponding signal handler. If the \module{signal} module is supported, this can invoke a signal handler written in Python. In all -cases, the default effect for \code{SIGINT} is to raise the -\code{KeyboadInterrupt} exception. If an exception is raised the -error indicator is set and the function returns 1; otherwise the -function returns 0. The error indicator may or may not be cleared if -it was previously set. +cases, the default effect for \constant{SIGINT} is to raise the +\exception{KeyboadInterrupt} exception. If an exception is raised the +error indicator is set and the function returns \code{1}; otherwise +the function returns \code{0}. The error indicator may or may not be +cleared if it was previously set. \end{cfuncdesc} \begin{cfuncdesc}{void}{PyErr_SetInterrupt}{} This function is obsolete (XXX or platform dependent?). It simulates -the effect of a \code{SIGINT} signal arriving -- the next time -\code{PyErr_CheckSignals()} is called, \code{KeyboadInterrupt} will be -raised. +the effect of a \constant{SIGINT} signal arriving --- the next time +\cfunction{PyErr_CheckSignals()} is called, +\exception{KeyboadInterrupt} will be raised. \end{cfuncdesc} \begin{cfuncdesc}{PyObject *}{PyErr_NewException}{char *name, @@ -780,8 +796,8 @@ This utility function creates and returns a new exception object. The of the form \code{module.class}. The \var{base} and \var{dict} arguments are normally \NULL{}. Normally, this creates a class object derived from the root for all exceptions, the built-in name -\code{Exception} (accessible in \C{} as \code{PyExc_Exception}). In this -case the \code{__module__} attribute of the new class is set to the +\exception{Exception} (accessible in \C{} as \code{PyExc_Exception}). +In this case the \code{__module__} attribute of the new class is set to the first part (up to the last dot) of the \var{name} argument, and the class name is set to the last part (after the last dot). When the user has specified the \code{-X} command line option to use string @@ -797,10 +813,11 @@ variables and methods. \section{Standard Exceptions} All standard Python exceptions are available as global variables whose -names are \code{PyExc_} followed by the Python exception name. -These have the type \code{PyObject *}; they are all string objects. -For completeness, here are all the variables (the first four are new -in Python 1.5a4): +names are \samp{PyExc_} followed by the Python exception name. +These have the type \code{PyObject *}; they are all either class +objects or string objects, depending on the use of the \code{-X} +option to the interpreter. For completeness, here are all the +variables (the first four are new in Python 1.5a4): \code{PyExc_Exception}, \code{PyExc_StandardError}, \code{PyExc_ArithmeticError}, @@ -835,18 +852,18 @@ values. \section{OS Utilities} \begin{cfuncdesc}{int}{Py_FdIsInteractive}{FILE *fp, char *filename} -Return true (nonzero) if the standard I/O file \code{fp} with name -\code{filename} is deemed interactive. This is the case for files for -which \code{isatty(fileno(fp))} is true. If the global flag +Return true (nonzero) if the standard I/O file \var{fp} with name +\var{filename} is deemed interactive. This is the case for files for +which \samp{isatty(fileno(\var{fp}))} is true. If the global flag \code{Py_InteractiveFlag} is true, this function also returns true if -the \code{name} pointer is \NULL{} or if the name is equal to one of +the \var{name} pointer is \NULL{} or if the name is equal to one of the strings \code{"<stdin>"} or \code{"???"}. \end{cfuncdesc} \begin{cfuncdesc}{long}{PyOS_GetLastModificationTime}{char *filename} -Return the time of last modification of the file \code{filename}. +Return the time of last modification of the file \var{filename}. The result is encoded in the same way as the timestamp returned by -the standard \C{} library function \code{time()}. +the standard \C{} library function \cfunction{time()}. \end{cfuncdesc} @@ -857,13 +874,15 @@ Print a fatal error message and kill the process. No cleanup is performed. This function should only be invoked when a condition is detected that would make it dangerous to continue using the Python interpreter; e.g., when the object administration appears to be -corrupted. On \UNIX{}, the standard \C{} library function \code{abort()} is -called which will attempt to produce a \file{core} file. +corrupted. On \UNIX{}, the standard \C{} library function +\cfunction{abort()} is called which will attempt to produce a +\file{core} file. \end{cfuncdesc} \begin{cfuncdesc}{void}{Py_Exit}{int status} -Exit the current process. This calls \code{Py_Finalize()} and then -calls the standard \C{} library function \code{exit(\var{status})}. +Exit the current process. This calls \cfunction{Py_Finalize()} and +then calls the standard \C{} library function +\code{exit(\var{status})}. \end{cfuncdesc} \begin{cfuncdesc}{int}{Py_AtExit}{void (*func) ()} @@ -882,7 +901,7 @@ by \var{func}. \section{Importing Modules} \begin{cfuncdesc}{PyObject *}{PyImport_ImportModule}{char *name} -This is a simplified interface to \code{PyImport_ImportModuleEx} +This is a simplified interface to \cfunction{PyImport_ImportModuleEx()} below, leaving the \var{globals} and \var{locals} arguments set to \NULL{}. When the \var{name} argument contains a dot (i.e., when it specifies a submodule of a package), the \var{fromlist} argument is @@ -899,31 +918,31 @@ be created in this case). \begin{cfuncdesc}{PyObject *}{PyImport_ImportModuleEx}{char *name, PyObject *globals, PyObject *locals, PyObject *fromlist} \strong{(NEW in 1.5a4!)} Import a module. This is best described by referring to the built-in -Python function \code{__import()__}, as the standard -\code{__import__()} function calls this function directly. +Python function \function{__import__()}, as the standard +\function{__import__()} function calls this function directly. The return value is a new reference to the imported module or top-level package, or \NULL{} with an exception set on failure (the module may still be created in this case). Like for -\code{__import__()}, the return value when a submodule of a package -was requested is normally the top-level package, unless a non-empty -\var{fromlist} was given. +\function{__import__()}, the return value when a submodule of a +package was requested is normally the top-level package, unless a +non-empty \var{fromlist} was given. \end{cfuncdesc} \begin{cfuncdesc}{PyObject *}{PyImport_Import}{PyObject *name} This is a higher-level interface that calls the current ``import hook -function''. It invokes the \code{__import__()} function from the +function''. It invokes the \function{__import__()} function from the \code{__builtins__} of the current globals. This means that the import is done using whatever import hooks are installed in the -current environment, e.g. by \code{rexec} or \code{ihooks}. +current environment, e.g. by \module{rexec} or \module{ihooks}. \end{cfuncdesc} \begin{cfuncdesc}{PyObject *}{PyImport_ReloadModule}{PyObject *m} Reload a module. This is best described by referring to the built-in -Python function \code{reload()}, as the standard \code{reload()} -function calls this function directly. Return a new reference to the -reloaded module, or \NULL{} with an exception set on failure (the -module still exists in this case). +Python function \function{reload()}, as the standard +\function{reload()} function calls this function directly. Return a +new reference to the reloaded module, or \NULL{} with an exception set +on failure (the module still exists in this case). \end{cfuncdesc} \begin{cfuncdesc}{PyObject *}{PyImport_AddModule}{char *name} @@ -939,15 +958,15 @@ exception set on failure. \begin{cfuncdesc}{PyObject *}{PyImport_ExecCodeModule}{char *name, PyObject *co} Given a module name (possibly of the form \code{package.module}) and a code object read from a Python bytecode file or obtained from the -built-in function \code{compile()}, load the module. Return a new +built-in function \function{compile()}, load the module. Return a new reference to the module object, or \NULL{} with an exception set if an error occurred (the module may still be created in this case). (This function would reload the module if it was already imported.) \end{cfuncdesc} \begin{cfuncdesc}{long}{PyImport_GetMagicNumber}{} -Return the magic number for Python bytecode files (a.k.a. \code{.pyc} -and \code{.pyo} files). The magic number should be present in the +Return the magic number for Python bytecode files (a.k.a. \file{.pyc} +and \file{.pyo} files). The magic number should be present in the first four bytes of the bytecode file, in little-endian byte order. \end{cfuncdesc} @@ -981,8 +1000,8 @@ For internal use only. Load a frozen module. Return \code{1} for success, \code{0} if the module is not found, and \code{-1} with an exception set if the initialization failed. To access the imported module on a successful -load, use \code{PyImport_ImportModule())}. -(Note the misnomer -- this function would reload the module if it was +load, use \cfunction{PyImport_ImportModule()}. +(Note the misnomer --- this function would reload the module if it was already imported.) \end{cfuncdesc} @@ -1018,512 +1037,526 @@ for which they do not apply, they will flag a Python exception. \section{Object Protocol} \begin{cfuncdesc}{int}{PyObject_Print}{PyObject *o, FILE *fp, int flags} -Print an object \code{o}, on file \code{fp}. Returns -1 on error +Print an object \var{o}, on file \var{fp}. Returns \code{-1} on error The flags argument is used to enable certain printing -options. The only option currently supported is \code{Py_Print_RAW}. +options. The only option currently supported is +\constant{Py_Print_RAW}. \end{cfuncdesc} \begin{cfuncdesc}{int}{PyObject_HasAttrString}{PyObject *o, char *attr_name} -Returns 1 if o has the attribute attr_name, and 0 otherwise. -This is equivalent to the Python expression: -\code{hasattr(o,attr_name)}. +Returns \code{1} if \var{o} has the attribute \var{attr_name}, and +\code{0} otherwise. This is equivalent to the Python expression +\samp{hasattr(\var{o}, \var{attr_name})}. This function always succeeds. \end{cfuncdesc} \begin{cfuncdesc}{PyObject*}{PyObject_GetAttrString}{PyObject *o, char *attr_name} -Retrieve an attribute named attr_name from object o. +Retrieve an attribute named \var{attr_name} from object \var{o}. Returns the attribute value on success, or \NULL{} on failure. -This is the equivalent of the Python expression: \code{o.attr_name}. +This is the equivalent of the Python expression +\samp{\var{o}.\var{attr_name}}. \end{cfuncdesc} \begin{cfuncdesc}{int}{PyObject_HasAttr}{PyObject *o, PyObject *attr_name} -Returns 1 if o has the attribute attr_name, and 0 otherwise. -This is equivalent to the Python expression: -\code{hasattr(o,attr_name)}. +Returns \code{1} if \var{o} has the attribute \var{attr_name}, and +\code{0} otherwise. This is equivalent to the Python expression +\samp{hasattr(\var{o}, \var{attr_name})}. This function always succeeds. \end{cfuncdesc} \begin{cfuncdesc}{PyObject*}{PyObject_GetAttr}{PyObject *o, PyObject *attr_name} -Retrieve an attribute named attr_name from object o. +Retrieve an attribute named \var{attr_name} from object \var{o}. Returns the attribute value on success, or \NULL{} on failure. -This is the equivalent of the Python expression: o.attr_name. +This is the equivalent of the Python expression +\samp{\var{o}.\var{attr_name}}. \end{cfuncdesc} \begin{cfuncdesc}{int}{PyObject_SetAttrString}{PyObject *o, char *attr_name, PyObject *v} -Set the value of the attribute named \code{attr_name}, for object \code{o}, -to the value \code{v}. Returns -1 on failure. This is -the equivalent of the Python statement: \code{o.attr_name=v}. +Set the value of the attribute named \var{attr_name}, for object +\var{o}, to the value \var{v}. Returns \code{-1} on failure. This is +the equivalent of the Python statement \samp{\var{o}.\var{attr_name} = +\var{v}}. \end{cfuncdesc} \begin{cfuncdesc}{int}{PyObject_SetAttr}{PyObject *o, PyObject *attr_name, PyObject *v} -Set the value of the attribute named \code{attr_name}, for -object \code{o}, -to the value \code{v}. Returns -1 on failure. This is -the equivalent of the Python statement: \code{o.attr_name=v}. +Set the value of the attribute named \var{attr_name}, for +object \var{o}, +to the value \var{v}. Returns \code{-1} on failure. This is +the equivalent of the Python statement \samp{\var{o}.\var{attr_name} = +\var{v}}. \end{cfuncdesc} \begin{cfuncdesc}{int}{PyObject_DelAttrString}{PyObject *o, char *attr_name} -Delete attribute named \code{attr_name}, for object \code{o}. Returns -1 on -failure. This is the equivalent of the Python -statement: \code{del o.attr_name}. +Delete attribute named \var{attr_name}, for object \var{o}. Returns +\code{-1} on failure. This is the equivalent of the Python +statement: \samp{del \var{o}.\var{attr_name}}. \end{cfuncdesc} \begin{cfuncdesc}{int}{PyObject_DelAttr}{PyObject *o, PyObject *attr_name} -Delete attribute named \code{attr_name}, for object \code{o}. Returns -1 on -failure. This is the equivalent of the Python -statement: \code{del o.attr_name}. +Delete attribute named \var{attr_name}, for object \var{o}. Returns +\code{-1} on failure. This is the equivalent of the Python +statement \samp{del \var{o}.\var{attr_name}}. \end{cfuncdesc} \begin{cfuncdesc}{int}{PyObject_Cmp}{PyObject *o1, PyObject *o2, int *result} -Compare the values of \code{o1} and \code{o2} using a routine provided by -\code{o1}, if one exists, otherwise with a routine provided by \code{o2}. -The result of the comparison is returned in \code{result}. Returns --1 on failure. This is the equivalent of the Python -statement: \code{result=cmp(o1,o2)}. +Compare the values of \var{o1} and \var{o2} using a routine provided +by \var{o1}, if one exists, otherwise with a routine provided by +\var{o2}. The result of the comparison is returned in \var{result}. +Returns \code{-1} on failure. This is the equivalent of the Python +statement \samp{\var{result} = cmp(\var{o1}, \var{o2})}. \end{cfuncdesc} \begin{cfuncdesc}{int}{PyObject_Compare}{PyObject *o1, PyObject *o2} -Compare the values of \code{o1} and \code{o2} using a routine provided by -\code{o1}, if one exists, otherwise with a routine provided by \code{o2}. -Returns the result of the comparison on success. On error, -the value returned is undefined. This is equivalent to the -Python expression: \code{cmp(o1,o2)}. +Compare the values of \var{o1} and \var{o2} using a routine provided +by \var{o1}, if one exists, otherwise with a routine provided by +\var{o2}. Returns the result of the comparison on success. On error, +the value returned is undefined; use \cfunction{PyErr_Occurred()} to +detect an error. This is equivalent to the +Python expression \samp{cmp(\var{o1}, \var{o2})}. \end{cfuncdesc} \begin{cfuncdesc}{PyObject*}{PyObject_Repr}{PyObject *o} -Compute the string representation of object, \code{o}. Returns the +Compute the string representation of object, \var{o}. Returns the string representation on success, \NULL{} on failure. This is -the equivalent of the Python expression: \code{repr(o)}. -Called by the \code{repr()} built-in function and by reverse quotes. +the equivalent of the Python expression \samp{repr(\var{o})}. +Called by the \function{repr()}\bifuncindex{repr} built-in function +and by reverse quotes. \end{cfuncdesc} \begin{cfuncdesc}{PyObject*}{PyObject_Str}{PyObject *o} -Compute the string representation of object, \code{o}. Returns the +Compute the string representation of object \var{o}. Returns the string representation on success, \NULL{} on failure. This is -the equivalent of the Python expression: \code{str(o)}. -Called by the \code{str()} built-in function and by the \code{print} -statement. +the equivalent of the Python expression \samp{str(\var{o})}. +Called by the \function{str()}\bifuncindex{str} built-in function and +by the \keyword{print} statement. \end{cfuncdesc} \begin{cfuncdesc}{int}{PyCallable_Check}{PyObject *o} -Determine if the object \code{o}, is callable. Return 1 if the -object is callable and 0 otherwise. +Determine if the object \var{o}, is callable. Return \code{1} if the +object is callable and \code{0} otherwise. This function always succeeds. \end{cfuncdesc} \begin{cfuncdesc}{PyObject*}{PyObject_CallObject}{PyObject *callable_object, PyObject *args} -Call a callable Python object \code{callable_object}, with -arguments given by the tuple \code{args}. If no arguments are +Call a callable Python object \var{callable_object}, with +arguments given by the tuple \var{args}. If no arguments are needed, then args may be \NULL{}. Returns the result of the call on success, or \NULL{} on failure. This is the equivalent -of the Python expression: \code{apply(o, args)}. +of the Python expression \samp{apply(\var{o}, \var{args})}. \end{cfuncdesc} \begin{cfuncdesc}{PyObject*}{PyObject_CallFunction}{PyObject *callable_object, char *format, ...} -Call a callable Python object \code{callable_object}, with a +Call a callable Python object \var{callable_object}, with a variable number of \C{} arguments. The \C{} arguments are described -using a mkvalue-style format string. The format may be \NULL{}, -indicating that no arguments are provided. Returns the +using a \cfunction{Py_BuildValue()} style format string. The format may +be \NULL{}, indicating that no arguments are provided. Returns the result of the call on success, or \NULL{} on failure. This is -the equivalent of the Python expression: \code{apply(o,args)}. +the equivalent of the Python expression \samp{apply(\var{o}, +\var{args})}. \end{cfuncdesc} \begin{cfuncdesc}{PyObject*}{PyObject_CallMethod}{PyObject *o, char *m, char *format, ...} -Call the method named \code{m} of object \code{o} with a variable number of -C arguments. The \C{} arguments are described by a mkvalue -format string. The format may be \NULL{}, indicating that no -arguments are provided. Returns the result of the call on -success, or \NULL{} on failure. This is the equivalent of the -Python expression: \code{o.method(args)}. -Note that Special method names, such as "\code{__add__}", -"\code{__getitem__}", and so on are not supported. The specific +Call the method named \var{m} of object \var{o} with a variable number +of C arguments. The \C{} arguments are described by a +\cfunction{Py_BuildValue()} format string. The format may be \NULL{}, +indicating that no arguments are provided. Returns the result of the +call on success, or \NULL{} on failure. This is the equivalent of the +Python expression \samp{\var{o}.\var{method}(\var{args})}. +Note that Special method names, such as \method{__add__()}, +\method{__getitem__()}, and so on are not supported. The specific abstract-object routines for these must be used. \end{cfuncdesc} \begin{cfuncdesc}{int}{PyObject_Hash}{PyObject *o} -Compute and return the hash value of an object \code{o}. On -failure, return -1. This is the equivalent of the Python -expression: \code{hash(o)}. +Compute and return the hash value of an object \var{o}. On +failure, return \code{-1}. This is the equivalent of the Python +expression \samp{hash(\var{o})}. \end{cfuncdesc} \begin{cfuncdesc}{int}{PyObject_IsTrue}{PyObject *o} -Returns 1 if the object \code{o} is considered to be true, and -0 otherwise. This is equivalent to the Python expression: -\code{not not o}. +Returns \code{1} if the object \var{o} is considered to be true, and +\code{0} otherwise. This is equivalent to the Python expression +\samp{not not \var{o}}. This function always succeeds. \end{cfuncdesc} \begin{cfuncdesc}{PyObject*}{PyObject_Type}{PyObject *o} On success, returns a type object corresponding to the object -type of object \code{o}. On failure, returns \NULL{}. This is -equivalent to the Python expression: \code{type(o)}. +type of object \var{o}. On failure, returns \NULL{}. This is +equivalent to the Python expression \samp{type(\var{o})}. \end{cfuncdesc} \begin{cfuncdesc}{int}{PyObject_Length}{PyObject *o} -Return the length of object \code{o}. If the object \code{o} provides +Return the length of object \var{o}. If the object \var{o} provides both sequence and mapping protocols, the sequence length is -returned. On error, -1 is returned. This is the equivalent -to the Python expression: \code{len(o)}. +returned. On error, \code{-1} is returned. This is the equivalent +to the Python expression \samp{len(\var{o})}. \end{cfuncdesc} \begin{cfuncdesc}{PyObject*}{PyObject_GetItem}{PyObject *o, PyObject *key} -Return element of \code{o} corresponding to the object \code{key} or \NULL{} -on failure. This is the equivalent of the Python expression: -\code{o[key]}. +Return element of \var{o} corresponding to the object \var{key} or +\NULL{} on failure. This is the equivalent of the Python expression +\samp{\var{o}[\var{key}]}. \end{cfuncdesc} \begin{cfuncdesc}{int}{PyObject_SetItem}{PyObject *o, PyObject *key, PyObject *v} -Map the object \code{key} to the value \code{v}. -Returns -1 on failure. This is the equivalent -of the Python statement: \code{o[key]=v}. +Map the object \var{key} to the value \var{v}. +Returns \code{-1} on failure. This is the equivalent +of the Python statement \samp{\var{o}[\var{key}] = \var{v}}. \end{cfuncdesc} \begin{cfuncdesc}{int}{PyObject_DelItem}{PyObject *o, PyObject *key, PyObject *v} -Delete the mapping for \code{key} from \code{*o}. Returns -1 -on failure. -This is the equivalent of the Python statement: \code{del o[key]}. +Delete the mapping for \var{key} from \var{o}. Returns \code{-1} on +failure. This is the equivalent of the Python statement \samp{del +\var{o}[\var{key}]}. \end{cfuncdesc} \section{Number Protocol} \begin{cfuncdesc}{int}{PyNumber_Check}{PyObject *o} -Returns 1 if the object \code{o} provides numeric protocols, and +Returns \code{1} if the object \var{o} provides numeric protocols, and false otherwise. This function always succeeds. \end{cfuncdesc} \begin{cfuncdesc}{PyObject*}{PyNumber_Add}{PyObject *o1, PyObject *o2} -Returns the result of adding \code{o1} and \code{o2}, or null on failure. -This is the equivalent of the Python expression: \code{o1+o2}. +Returns the result of adding \var{o1} and \var{o2}, or \NULL{} on +failure. This is the equivalent of the Python expression +\samp{\var{o1} + \var{o2}}. \end{cfuncdesc} \begin{cfuncdesc}{PyObject*}{PyNumber_Subtract}{PyObject *o1, PyObject *o2} -Returns the result of subtracting \code{o2} from \code{o1}, or null on -failure. This is the equivalent of the Python expression: -\code{o1-o2}. +Returns the result of subtracting \var{o2} from \var{o1}, or \NULL{} +on failure. This is the equivalent of the Python expression +\samp{\var{o1} - \var{o2}}. \end{cfuncdesc} \begin{cfuncdesc}{PyObject*}{PyNumber_Multiply}{PyObject *o1, PyObject *o2} -Returns the result of multiplying \code{o1} and \code{o2}, or null on -failure. This is the equivalent of the Python expression: -\code{o1*o2}. +Returns the result of multiplying \var{o1} and \var{o2}, or \NULL{} on +failure. This is the equivalent of the Python expression +\samp{\var{o1} * \var{o2}}. \end{cfuncdesc} \begin{cfuncdesc}{PyObject*}{PyNumber_Divide}{PyObject *o1, PyObject *o2} -Returns the result of dividing \code{o1} by \code{o2}, or null on failure. -This is the equivalent of the Python expression: \code{o1/o2}. +Returns the result of dividing \var{o1} by \var{o2}, or \NULL{} on +failure. +This is the equivalent of the Python expression \samp{\var{o1} / +\var{o2}}. \end{cfuncdesc} \begin{cfuncdesc}{PyObject*}{PyNumber_Remainder}{PyObject *o1, PyObject *o2} -Returns the remainder of dividing \code{o1} by \code{o2}, or null on -failure. This is the equivalent of the Python expression: -\code{o1\%o2}. +Returns the remainder of dividing \var{o1} by \var{o2}, or \NULL{} on +failure. This is the equivalent of the Python expression +\samp{\var{o1} \% \var{o2}}. \end{cfuncdesc} \begin{cfuncdesc}{PyObject*}{PyNumber_Divmod}{PyObject *o1, PyObject *o2} -See the built-in function divmod. Returns \NULL{} on failure. -This is the equivalent of the Python expression: -\code{divmod(o1,o2)}. +See the built-in function \function{divmod()}. Returns \NULL{} on +failure. This is the equivalent of the Python expression +\samp{divmod(\var{o1}, \var{o2})}. \end{cfuncdesc} \begin{cfuncdesc}{PyObject*}{PyNumber_Power}{PyObject *o1, PyObject *o2, PyObject *o3} -See the built-in function pow. Returns \NULL{} on failure. -This is the equivalent of the Python expression: -\code{pow(o1,o2,o3)}, where \code{o3} is optional. +See the built-in function \function{pow()}. Returns \NULL{} on +failure. This is the equivalent of the Python expression +\samp{pow(\var{o1}, \var{o2}, \var{o3})}, where \var{o3} is optional. +If \var{o3} is to be ignored, pass \code{Py_None} in its place. \end{cfuncdesc} \begin{cfuncdesc}{PyObject*}{PyNumber_Negative}{PyObject *o} -Returns the negation of \code{o} on success, or null on failure. -This is the equivalent of the Python expression: \code{-o}. +Returns the negation of \var{o} on success, or \NULL{} on failure. +This is the equivalent of the Python expression \samp{-\var{o}}. \end{cfuncdesc} \begin{cfuncdesc}{PyObject*}{PyNumber_Positive}{PyObject *o} -Returns \code{o} on success, or \NULL{} on failure. -This is the equivalent of the Python expression: \code{+o}. +Returns \var{o} on success, or \NULL{} on failure. +This is the equivalent of the Python expression \samp{+\var{o}}. \end{cfuncdesc} \begin{cfuncdesc}{PyObject*}{PyNumber_Absolute}{PyObject *o} -Returns the absolute value of \code{o}, or null on failure. This is -the equivalent of the Python expression: \code{abs(o)}. +Returns the absolute value of \var{o}, or \NULL{} on failure. This is +the equivalent of the Python expression \samp{abs(\var{o})}. \end{cfuncdesc} \begin{cfuncdesc}{PyObject*}{PyNumber_Invert}{PyObject *o} -Returns the bitwise negation of \code{o} on success, or \NULL{} on -failure. This is the equivalent of the Python expression: -\code{\~o}. +Returns the bitwise negation of \var{o} on success, or \NULL{} on +failure. This is the equivalent of the Python expression +\samp{\~\var{o}}. \end{cfuncdesc} \begin{cfuncdesc}{PyObject*}{PyNumber_Lshift}{PyObject *o1, PyObject *o2} -Returns the result of left shifting \code{o1} by \code{o2} on success, or -\NULL{} on failure. This is the equivalent of the Python -expression: \code{o1 << o2}. +Returns the result of left shifting \var{o1} by \var{o2} on success, +or \NULL{} on failure. This is the equivalent of the Python +expression \samp{\var{o1} << \var{o2}}. \end{cfuncdesc} \begin{cfuncdesc}{PyObject*}{PyNumber_Rshift}{PyObject *o1, PyObject *o2} -Returns the result of right shifting \code{o1} by \code{o2} on success, or -\NULL{} on failure. This is the equivalent of the Python -expression: \code{o1 >> o2}. +Returns the result of right shifting \var{o1} by \var{o2} on success, +or \NULL{} on failure. This is the equivalent of the Python +expression \samp{\var{o1} >> \var{o2}}. \end{cfuncdesc} \begin{cfuncdesc}{PyObject*}{PyNumber_And}{PyObject *o1, PyObject *o2} -Returns the result of "anding" \code{o2} and \code{o2} on success and \NULL{} -on failure. This is the equivalent of the Python -expression: \code{o1 and o2}. +Returns the result of ``anding'' \var{o2} and \var{o2} on success and +\NULL{} on failure. This is the equivalent of the Python +expression \samp{\var{o1} and \var{o2}}. \end{cfuncdesc} \begin{cfuncdesc}{PyObject*}{PyNumber_Xor}{PyObject *o1, PyObject *o2} -Returns the bitwise exclusive or of \code{o1} by \code{o2} on success, or -\NULL{} on failure. This is the equivalent of the Python -expression: \code{o1\^{ }o2}. +Returns the bitwise exclusive or of \var{o1} by \var{o2} on success, +or \NULL{} on failure. This is the equivalent of the Python +expression \samp{\var{o1} \^{ }\var{o2}}. \end{cfuncdesc} \begin{cfuncdesc}{PyObject*}{PyNumber_Or}{PyObject *o1, PyObject *o2} -Returns the result of \code{o1} and \code{o2} on success, or \NULL{} on -failure. This is the equivalent of the Python expression: -\code{o1 or o2}. +Returns the result of \var{o1} and \var{o2} on success, or \NULL{} on +failure. This is the equivalent of the Python expression +\samp{\var{o1} or \var{o2}}. \end{cfuncdesc} -\begin{cfuncdesc}{PyObject*}{PyNumber_Coerce}{PyObject *o1, PyObject *o2} +\begin{cfuncdesc}{PyObject*}{PyNumber_Coerce}{PyObject **p1, PyObject **p2} This function takes the addresses of two variables of type \code{PyObject*}. -If the objects pointed to by \code{*p1} and \code{*p2} have the same type, -increment their reference count and return 0 (success). -If the objects can be converted to a common numeric type, -replace \code{*p1} and \code{*p2} by their converted value (with 'new' -reference counts), and return 0. +If the objects pointed to by \code{*\var{p1}} and \code{*\var{p2}} +have the same type, increment their reference count and return +\code{0} (success). If the objects can be converted to a common +numeric type, replace \code{*p1} and \code{*p2} by their converted +value (with 'new' reference counts), and return \code{0}. If no conversion is possible, or if some other error occurs, -return -1 (failure) and don't increment the reference counts. -The call \code{PyNumber_Coerce(\&o1, \&o2)} is equivalent to the Python -statement \code{o1, o2 = coerce(o1, o2)}. +return \code{-1} (failure) and don't increment the reference counts. +The call \code{PyNumber_Coerce(\&o1, \&o2)} is equivalent to the +Python statement \samp{\var{o1}, \var{o2} = coerce(\var{o1}, +\var{o2})}. \end{cfuncdesc} \begin{cfuncdesc}{PyObject*}{PyNumber_Int}{PyObject *o} -Returns the \code{o} converted to an integer object on success, or +Returns the \var{o} converted to an integer object on success, or \NULL{} on failure. This is the equivalent of the Python -expression: \code{int(o)}. +expression \samp{int(\var{o})}. \end{cfuncdesc} \begin{cfuncdesc}{PyObject*}{PyNumber_Long}{PyObject *o} -Returns the \code{o} converted to a long integer object on success, +Returns the \var{o} converted to a long integer object on success, or \NULL{} on failure. This is the equivalent of the Python -expression: \code{long(o)}. +expression \samp{long(\var{o})}. \end{cfuncdesc} \begin{cfuncdesc}{PyObject*}{PyNumber_Float}{PyObject *o} -Returns the \code{o} converted to a float object on success, or \NULL{} -on failure. This is the equivalent of the Python expression: -\code{float(o)}. +Returns the \var{o} converted to a float object on success, or \NULL{} +on failure. This is the equivalent of the Python expression +\samp{float(\var{o})}. \end{cfuncdesc} \section{Sequence Protocol} \begin{cfuncdesc}{int}{PySequence_Check}{PyObject *o} -Return 1 if the object provides sequence protocol, and 0 +Return \code{1} if the object provides sequence protocol, and \code{0} otherwise. This function always succeeds. \end{cfuncdesc} \begin{cfuncdesc}{PyObject*}{PySequence_Concat}{PyObject *o1, PyObject *o2} -Return the concatenation of \code{o1} and \code{o2} on success, and \NULL{} on +Return the concatenation of \var{o1} and \var{o2} on success, and \NULL{} on failure. This is the equivalent of the Python -expression: \code{o1+o2}. +expression \samp{\var{o1} + \var{o2}}. \end{cfuncdesc} \begin{cfuncdesc}{PyObject*}{PySequence_Repeat}{PyObject *o, int count} -Return the result of repeating sequence object \code{o} \code{count} times, -or \NULL{} on failure. This is the equivalent of the Python -expression: \code{o*count}. +Return the result of repeating sequence object \var{o} \var{count} +times, or \NULL{} on failure. This is the equivalent of the Python +expression \samp{\var{o} * \var{count}}. \end{cfuncdesc} \begin{cfuncdesc}{PyObject*}{PySequence_GetItem}{PyObject *o, int i} -Return the ith element of \code{o}, or \NULL{} on failure. This is the -equivalent of the Python expression: \code{o[i]}. +Return the \var{i}th element of \var{o}, or \NULL{} on failure. This +is the equivalent of the Python expression \samp{\var{o}[\var{i}]}. \end{cfuncdesc} \begin{cfuncdesc}{PyObject*}{PySequence_GetSlice}{PyObject *o, int i1, int i2} -Return the slice of sequence object \code{o} between \code{i1} and \code{i2}, or -\NULL{} on failure. This is the equivalent of the Python -expression, \code{o[i1:i2]}. +Return the slice of sequence object \var{o} between \var{i1} and +\var{i2}, or \NULL{} on failure. This is the equivalent of the Python +expression \samp{\var{o}[\var{i1}:\var{i2}]}. \end{cfuncdesc} \begin{cfuncdesc}{int}{PySequence_SetItem}{PyObject *o, int i, PyObject *v} -Assign object \code{v} to the \code{i}th element of \code{o}. -Returns -1 on failure. This is the equivalent of the Python -statement, \code{o[i]=v}. +Assign object \var{v} to the \var{i}th element of \var{o}. +Returns \code{-1} on failure. This is the equivalent of the Python +statement \samp{\var{o}[\var{i}] = \var{v}}. \end{cfuncdesc} \begin{cfuncdesc}{int}{PySequence_DelItem}{PyObject *o, int i} -Delete the \code{i}th element of object \code{v}. Returns --1 on failure. This is the equivalent of the Python -statement: \code{del o[i]}. +Delete the \var{i}th element of object \var{v}. Returns +\code{-1} on failure. This is the equivalent of the Python +statement \samp{del \var{o}[\var{i}]}. \end{cfuncdesc} \begin{cfuncdesc}{int}{PySequence_SetSlice}{PyObject *o, int i1, int i2, PyObject *v} -Assign the sequence object \code{v} to the slice in sequence -object \code{o} from \code{i1} to \code{i2}. This is the equivalent of the Python -statement, \code{o[i1:i2]=v}. +Assign the sequence object \var{v} to the slice in sequence +object \var{o} from \var{i1} to \var{i2}. This is the equivalent of +the Python statement \samp{\var{o}[\var{i1}:\var{i2}] = \var{v}}. \end{cfuncdesc} \begin{cfuncdesc}{int}{PySequence_DelSlice}{PyObject *o, int i1, int i2} -Delete the slice in sequence object, \code{o}, from \code{i1} to \code{i2}. -Returns -1 on failure. This is the equivalent of the Python -statement: \code{del o[i1:i2]}. +Delete the slice in sequence object \var{o} from \var{i1} to \var{i2}. +Returns \code{-1} on failure. This is the equivalent of the Python +statement \samp{del \var{o}[\var{i1}:\var{i2}]}. \end{cfuncdesc} \begin{cfuncdesc}{PyObject*}{PySequence_Tuple}{PyObject *o} -Returns the \code{o} as a tuple on success, and \NULL{} on failure. -This is equivalent to the Python expression: \code{tuple(o)}. +Returns the \var{o} as a tuple on success, and \NULL{} on failure. +This is equivalent to the Python expression \code{tuple(\var{o})}. \end{cfuncdesc} \begin{cfuncdesc}{int}{PySequence_Count}{PyObject *o, PyObject *value} -Return the number of occurrences of \code{value} on \code{o}, that is, -return the number of keys for which \code{o[key]==value}. On -failure, return -1. This is equivalent to the Python -expression: \code{o.count(value)}. +Return the number of occurrences of \var{value} in \var{o}, that is, +return the number of keys for which \code{\var{o}[\var{key}] == +\var{value}}. On failure, return \code{-1}. This is equivalent to +the Python expression \samp{\var{o}.count(\var{value})}. \end{cfuncdesc} \begin{cfuncdesc}{int}{PySequence_In}{PyObject *o, PyObject *value} -Determine if \code{o} contains \code{value}. If an item in \code{o} is equal to -\code{value}, return 1, otherwise return 0. On error, return -1. This -is equivalent to the Python expression: \code{value in o}. +Determine if \var{o} contains \var{value}. If an item in \var{o} is +equal to \var{value}, return \code{1}, otherwise return \code{0}. On +error, return \code{-1}. This is equivalent to the Python expression +\samp{\var{value} in \var{o}}. \end{cfuncdesc} \begin{cfuncdesc}{int}{PySequence_Index}{PyObject *o, PyObject *value} -Return the first index for which \code{o[i]==value}. On error, -return -1. This is equivalent to the Python -expression: \code{o.index(value)}. +Return the first index \var{i} for which \code{\var{o}[\var{i}] == +\var{value}}. On error, return \code{-1}. This is equivalent to +the Python expression \samp{\var{o}.index(\var{value})}. \end{cfuncdesc} \section{Mapping Protocol} \begin{cfuncdesc}{int}{PyMapping_Check}{PyObject *o} -Return 1 if the object provides mapping protocol, and 0 +Return \code{1} if the object provides mapping protocol, and \code{0} otherwise. This function always succeeds. \end{cfuncdesc} \begin{cfuncdesc}{int}{PyMapping_Length}{PyObject *o} -Returns the number of keys in object \code{o} on success, and -1 on -failure. For objects that do not provide sequence protocol, -this is equivalent to the Python expression: \code{len(o)}. +Returns the number of keys in object \var{o} on success, and \code{-1} +on failure. For objects that do not provide sequence protocol, +this is equivalent to the Python expression \samp{len(\var{o})}. \end{cfuncdesc} \begin{cfuncdesc}{int}{PyMapping_DelItemString}{PyObject *o, char *key} -Remove the mapping for object \code{key} from the object \code{o}. -Return -1 on failure. This is equivalent to -the Python statement: \code{del o[key]}. +Remove the mapping for object \var{key} from the object \var{o}. +Return \code{-1} on failure. This is equivalent to +the Python statement \samp{del \var{o}[\var{key}]}. \end{cfuncdesc} \begin{cfuncdesc}{int}{PyMapping_DelItem}{PyObject *o, PyObject *key} -Remove the mapping for object \code{key} from the object \code{o}. -Return -1 on failure. This is equivalent to -the Python statement: \code{del o[key]}. +Remove the mapping for object \var{key} from the object \var{o}. +Return \code{-1} on failure. This is equivalent to +the Python statement \samp{del \var{o}[\var{key}]}. \end{cfuncdesc} \begin{cfuncdesc}{int}{PyMapping_HasKeyString}{PyObject *o, char *key} -On success, return 1 if the mapping object has the key \code{key} -and 0 otherwise. This is equivalent to the Python expression: -\code{o.has_key(key)}. +On success, return \code{1} if the mapping object has the key \var{key} +and \code{0} otherwise. This is equivalent to the Python expression +\samp{\var{o}.has_key(\var{key})}. This function always succeeds. \end{cfuncdesc} \begin{cfuncdesc}{int}{PyMapping_HasKey}{PyObject *o, PyObject *key} -Return 1 if the mapping object has the key \code{key} -and 0 otherwise. This is equivalent to the Python expression: -\code{o.has_key(key)}. +Return \code{1} if the mapping object has the key \var{key} and +\code{0} otherwise. This is equivalent to the Python expression +\samp{\var{o}.has_key(\var{key})}. This function always succeeds. \end{cfuncdesc} \begin{cfuncdesc}{PyObject*}{PyMapping_Keys}{PyObject *o} -On success, return a list of the keys in object \code{o}. On +On success, return a list of the keys in object \var{o}. On failure, return \NULL{}. This is equivalent to the Python -expression: \code{o.keys()}. +expression \samp{\var{o}.keys()}. \end{cfuncdesc} \begin{cfuncdesc}{PyObject*}{PyMapping_Values}{PyObject *o} -On success, return a list of the values in object \code{o}. On +On success, return a list of the values in object \var{o}. On failure, return \NULL{}. This is equivalent to the Python -expression: \code{o.values()}. +expression \samp{\var{o}.values()}. \end{cfuncdesc} \begin{cfuncdesc}{PyObject*}{PyMapping_Items}{PyObject *o} -On success, return a list of the items in object \code{o}, where +On success, return a list of the items in object \var{o}, where each item is a tuple containing a key-value pair. On failure, return \NULL{}. This is equivalent to the Python -expression: \code{o.items()}. +expression \samp{\var{o}.items()}. \end{cfuncdesc} \begin{cfuncdesc}{int}{PyMapping_Clear}{PyObject *o} -Make object \code{o} empty. Returns 1 on success and 0 on failure. -This is equivalent to the Python statement: -\code{for key in o.keys(): del o[key]} +Make object \var{o} empty. Returns \code{1} on success and \code{0} +on failure. This is equivalent to the Python statement +\samp{for key in \var{o}.keys(): del \var{o}[key]}. \end{cfuncdesc} \begin{cfuncdesc}{PyObject*}{PyMapping_GetItemString}{PyObject *o, char *key} -Return element of \code{o} corresponding to the object \code{key} or \NULL{} -on failure. This is the equivalent of the Python expression: -\code{o[key]}. +Return element of \var{o} corresponding to the object \var{key} or +\NULL{} on failure. This is the equivalent of the Python expression +\samp{\var{o}[\var{key}]}. \end{cfuncdesc} \begin{cfuncdesc}{PyObject*}{PyMapping_SetItemString}{PyObject *o, char *key, PyObject *v} -Map the object \code{key} to the value \code{v} in object \code{o}. Returns --1 on failure. This is the equivalent of the Python -statement: \code{o[key]=v}. +Map the object \var{key} to the value \var{v} in object \var{o}. +Returns \code{-1} on failure. This is the equivalent of the Python +statement \samp{\var{o}[\var{key}] = \var{v}}. \end{cfuncdesc} @@ -1531,41 +1564,41 @@ statement: \code{o[key]=v}. \begin{cfuncdesc}{PyObject*}{PyFile_FromString}{char *file_name, char *mode} On success, returns a new file object that is opened on the -file given by \code{file_name}, with a file mode given by \code{mode}, -where \code{mode} has the same semantics as the standard \C{} routine, -fopen. On failure, return -1. +file given by \var{file_name}, with a file mode given by \var{mode}, +where \var{mode} has the same semantics as the standard \C{} routine +\cfunction{fopen()}. On failure, return \code{-1}. \end{cfuncdesc} \begin{cfuncdesc}{PyObject*}{PyFile_FromFile}{FILE *fp, char *file_name, char *mode, int close_on_del} -Return a new file object for an already opened standard \C{} -file pointer, \code{fp}. A file name, \code{file_name}, and open mode, -\code{mode}, must be provided as well as a flag, \code{close_on_del}, that -indicates whether the file is to be closed when the file -object is destroyed. On failure, return -1. +Return a new file object for an already opened standard \C{} file +pointer, \var{fp}. A file name, \var{file_name}, and open mode, +\var{mode}, must be provided as well as a flag, \var{close_on_del}, +that indicates whether the file is to be closed when the file object +is destroyed. On failure, return \code{-1}. \end{cfuncdesc} \begin{cfuncdesc}{PyObject*}{PyFloat_FromDouble}{double v} -Returns a new float object with the value \code{v} on success, and +Returns a new float object with the value \var{v} on success, and \NULL{} on failure. \end{cfuncdesc} \begin{cfuncdesc}{PyObject*}{PyInt_FromLong}{long v} -Returns a new int object with the value \code{v} on success, and +Returns a new int object with the value \var{v} on success, and \NULL{} on failure. \end{cfuncdesc} -\begin{cfuncdesc}{PyObject*}{PyList_New}{int l} -Returns a new list of length \code{l} on success, and \NULL{} on +\begin{cfuncdesc}{PyObject*}{PyList_New}{int len} +Returns a new list of length \var{len} on success, and \NULL{} on failure. \end{cfuncdesc} \begin{cfuncdesc}{PyObject*}{PyLong_FromLong}{long v} -Returns a new long object with the value \code{v} on success, and +Returns a new long object with the value \var{v} on success, and \NULL{} on failure. \end{cfuncdesc} \begin{cfuncdesc}{PyObject*}{PyLong_FromDouble}{double v} -Returns a new long object with the value \code{v} on success, and +Returns a new long object with the value \var{v} on success, and \NULL{} on failure. \end{cfuncdesc} @@ -1575,17 +1608,18 @@ failure. \end{cfuncdesc} \begin{cfuncdesc}{PyObject*}{PyString_FromString}{char *v} -Returns a new string object with the value \code{v} on success, and +Returns a new string object with the value \var{v} on success, and \NULL{} on failure. \end{cfuncdesc} -\begin{cfuncdesc}{PyObject*}{PyString_FromStringAndSize}{char *v, int l} -Returns a new string object with the value \code{v} and length \code{l} -on success, and \NULL{} on failure. +\begin{cfuncdesc}{PyObject*}{PyString_FromStringAndSize}{char *v, int len} +Returns a new string object with the value \var{v} and length +\var{len} on success, and \NULL{} on failure. If \var{v} is \NULL{}, +the contents of the string are uninitialized. \end{cfuncdesc} -\begin{cfuncdesc}{PyObject*}{PyTuple_New}{int l} -Returns a new tuple of length \code{l} on success, and \NULL{} on +\begin{cfuncdesc}{PyObject*}{PyTuple_New}{int len} +Returns a new tuple of length \var{len} on success, and \NULL{} on failure. \end{cfuncdesc} @@ -1710,54 +1744,54 @@ Return true if the argument is a tuple object. \end{cfuncdesc} \begin{cfuncdesc}{PyTupleObject *}{PyTuple_New}{int s} -Return a new tuple object of size \code{s} +Return a new tuple object of size \var{s}. \end{cfuncdesc} \begin{cfuncdesc}{int}{PyTuple_Size}{PyTupleObject *p} -akes a pointer to a tuple object, and returns the size +Takes a pointer to a tuple object, and returns the size of that tuple. \end{cfuncdesc} \begin{cfuncdesc}{PyObject *}{PyTuple_GetItem}{PyTupleObject *p, int pos} -returns the object at position \code{pos} in the tuple pointed -to by \code{p}. +Returns the object at position \var{pos} in the tuple pointed +to by \var{p}. If \var{pos} is out of bounds, returns \NULL{} and +raises an \exception{IndexError} exception. \end{cfuncdesc} \begin{cfuncdesc}{PyObject *}{PyTuple_GET_ITEM}{PyTupleObject *p, int pos} -does the same, but does no checking of it's -arguments. +Does the same, but does no checking of its arguments. \end{cfuncdesc} \begin{cfuncdesc}{PyTupleObject *}{PyTuple_GetSlice}{PyTupleObject *p, int low, int high} -takes a slice of the tuple pointed to by \code{p} from -\code{low} to \code{high} and returns it as a new tuple. +Takes a slice of the tuple pointed to by \var{p} from +\var{low} to \var{high} and returns it as a new tuple. \end{cfuncdesc} \begin{cfuncdesc}{int}{PyTuple_SetItem}{PyTupleObject *p, int pos, PyObject *o} -inserts a reference to object \code{o} at position \code{pos} of -the tuple pointed to by \code{p}. It returns 0 on success. +Inserts a reference to object \var{o} at position \var{pos} of +the tuple pointed to by \var{p}. It returns \code{0} on success. \end{cfuncdesc} \begin{cfuncdesc}{void}{PyTuple_SET_ITEM}{PyTupleObject *p, int pos, PyObject *o} -does the same, but does no error checking, and +Does the same, but does no error checking, and should \emph{only} be used to fill in brand new tuples. \end{cfuncdesc} \begin{cfuncdesc}{PyTupleObject *}{_PyTuple_Resize}{PyTupleObject *p, int new, int last_is_sticky} -can be used to resize a tuple. Because tuples are +Can be used to resize a tuple. Because tuples are \emph{supposed} to be immutable, this should only be used if there is only one module referencing the object. Do \emph{not} use this if the tuple may -already be known to some other part of the code. \code{last_is_sticky} is -a flag - if set, the tuple will grow or shrink at the front, otherwise +already be known to some other part of the code. \var{last_is_sticky} is +a flag --- if set, the tuple will grow or shrink at the front, otherwise it will grow or shrink at the end. Think of this as destroying the old tuple and creating a new one, only more efficiently. \end{cfuncdesc} @@ -1774,7 +1808,7 @@ This instance of \code{PyTypeObject} represents the Python list type. \end{cvardesc} \begin{cfuncdesc}{int}{PyList_Check}{PyObject *p} -returns true if it's argument is a \code{PyListObject} +Returns true if its argument is a \code{PyListObject}. \end{cfuncdesc} \begin{cfuncdesc}{PyObject *}{PyList_New}{int size} @@ -1843,70 +1877,73 @@ This instance of \code{PyTypeObject} represents the Python dictionary type. \end{cvardesc} \begin{cfuncdesc}{int}{PyDict_Check}{PyObject *p} -returns true if it's argument is a PyDictObject +Returns true if its argument is a \code{PyDictObject}. \end{cfuncdesc} \begin{cfuncdesc}{PyDictObject *}{PyDict_New}{} -returns a new empty dictionary. +Returns a new empty dictionary. \end{cfuncdesc} \begin{cfuncdesc}{void}{PyDict_Clear}{PyDictObject *p} -empties an existing dictionary and deletes it. +Empties an existing dictionary of all key/value pairs. \end{cfuncdesc} \begin{cfuncdesc}{int}{PyDict_SetItem}{PyDictObject *p, PyObject *key, PyObject *val} -inserts \code{value} into the dictionary with a key of -\code{key}. Both \code{key} and \code{value} should be PyObjects, and \code{key} should -be hashable. +Inserts \var{value} into the dictionary with a key of \var{key}. Both +\var{key} and \var{value} should be PyObjects, and \var{key} should be +hashable. \end{cfuncdesc} \begin{cfuncdesc}{int}{PyDict_SetItemString}{PyDictObject *p, char *key, PyObject *val} -inserts \code{value} into the dictionary using \code{key} -as a key. \code{key} should be a char * +Inserts \var{value} into the dictionary using \var{key} +as a key. \var{key} should be a \code{char *}. The key object is +created using \code{PyString_FromString(\var{key})}. \end{cfuncdesc} \begin{cfuncdesc}{int}{PyDict_DelItem}{PyDictObject *p, PyObject *key} -removes the entry in dictionary \code{p} with key \code{key}. -\code{key} is a PyObject. +Removes the entry in dictionary \var{p} with key \var{key}. +\var{key} is a PyObject. \end{cfuncdesc} \begin{cfuncdesc}{int}{PyDict_DelItemString}{PyDictObject *p, char *key} -removes the entry in dictionary \code{p} which has a key -specified by the \code{char *}\code{key}. +Removes the entry in dictionary \var{p} which has a key +specified by the \code{char *}\var{key}. \end{cfuncdesc} \begin{cfuncdesc}{PyObject *}{PyDict_GetItem}{PyDictObject *p, PyObject *key} -returns the object from dictionary \code{p} which has a key -\code{key}. +Returns the object from dictionary \var{p} which has a key +\var{key}. Returns \NULL{} if the key \var{key} is not present. \end{cfuncdesc} \begin{cfuncdesc}{PyObject *}{PyDict_GetItemString}{PyDictObject *p, char *key} -does the same, but \code{key} is specified as a +Does the same, but \var{key} is specified as a \code{char *}, rather than a \code{PyObject *}. \end{cfuncdesc} \begin{cfuncdesc}{PyListObject *}{PyDict_Items}{PyDictObject *p} -returns a PyListObject containing all the items -from the dictionary, as in the mapping method \code{items()} (see the Reference -Guide) +Returns a \code{PyListObject} containing all the items +from the dictionary, as in the mapping method \method{items()} (see +the \emph{Python Library Reference}). \end{cfuncdesc} \begin{cfuncdesc}{PyListObject *}{PyDict_Keys}{PyDictObject *p} -returns a PyListObject containing all the keys -from the dictionary, as in the mapping method \code{keys()} (see the Reference Guide) +Returns a \code{PyListObject} containing all the keys +from the dictionary, as in the mapping method \method{keys()} (see the +\emph{Python Library Reference}). \end{cfuncdesc} \begin{cfuncdesc}{PyListObject *}{PyDict_Values}{PyDictObject *p} -returns a PyListObject containing all the values -from the dictionary, as in the mapping method \code{values()} (see the Reference Guide) +Returns a \code{PyListObject} containing all the values +from the dictionary \var{p}, as in the mapping method +\method{values()} (see the \emph{Python Library Reference}). \end{cfuncdesc} \begin{cfuncdesc}{int}{PyDict_Size}{PyDictObject *p} -returns the number of items in the dictionary. +Returns the number of items in the dictionary. \end{cfuncdesc} \begin{cfuncdesc}{int}{PyDict_Next}{PyDictObject *p, @@ -1935,42 +1972,45 @@ integer type. \end{cfuncdesc} \begin{cfuncdesc}{PyIntObject *}{PyInt_FromLong}{long ival} -creates a new integer object with a value of \code{ival}. +Creates a new integer object with a value of \var{ival}. The current implementation keeps an array of integer objects for all -integers between -1 and 100, when you create an int in that range you -actually just get back a reference to the existing object. So it should -be possible to change the value of 1. I suspect the behaviour of python -in this case is undefined. :-) +integers between \code{-1} and \code{100}, when you create an int in +that range you actually just get back a reference to the existing +object. So it should be possible to change the value of \code{1}. I +suspect the behaviour of python in this case is undefined. :-) \end{cfuncdesc} \begin{cfuncdesc}{long}{PyInt_AS_LONG}{PyIntObject *io} -returns the value of the object \code{io}. +Returns the value of the object \var{io}. No error checking is +performed. \end{cfuncdesc} \begin{cfuncdesc}{long}{PyInt_AsLong}{PyObject *io} -will first attempt to cast the object to a PyIntObject, if -it is not already one, and the return it's value. +Will first attempt to cast the object to a \code{PyIntObject}, if +it is not already one, and then return its value. \end{cfuncdesc} \begin{cfuncdesc}{long}{PyInt_GetMax}{} -returns the systems idea of the largest int it can handle -(LONG_MAX, as defined in the system header files) +Returns the systems idea of the largest integer it can handle +(\constant{LONG_MAX}, as defined in the system header files). \end{cfuncdesc} \subsection{Long Integer Objects} \begin{ctypedesc}{PyLongObject} -This subtype of \code{PyObject} represents a Python long integer object. +This subtype of \code{PyObject} represents a Python long integer +object. \end{ctypedesc} \begin{cvardesc}{PyTypeObject}{PyLong_Type} -This instance of \code{PyTypeObject} represents the Python long integer type. +This instance of \code{PyTypeObject} represents the Python long +integer type. \end{cvardesc} \begin{cfuncdesc}{int}{PyLong_Check}{PyObject *p} -returns true if it's argument is a \code{PyLongObject} +Returns true if its argument is a \code{PyLongObject}. \end{cfuncdesc} \begin{cfuncdesc}{PyObject *}{PyLong_FromLong}{long} @@ -2005,16 +2045,17 @@ returns true if it's argument is a \code{PyLongObject} \subsection{Floating Point Objects} \begin{ctypedesc}{PyFloatObject} -This subtype of \code{PyObject} represents a Python floating point object. +This subtype of \code{PyObject} represents a Python floating point +object. \end{ctypedesc} \begin{cvardesc}{PyTypeObject}{PyFloat_Type} -This instance of \code{PyTypeObject} represents the Python floating +This instance of \code{PyTypeObject} represents the Python floating point type. \end{cvardesc} \begin{cfuncdesc}{int}{PyFloat_Check}{PyObject *p} -returns true if it's argument is a \code{PyFloatObject} +Returns true if its argument is a \code{PyFloatObject}. \end{cfuncdesc} \begin{cfuncdesc}{PyObject *}{PyFloat_FromDouble}{double} @@ -2033,10 +2074,17 @@ returns true if it's argument is a \code{PyFloatObject} \subsection{Complex Number Objects} \begin{ctypedesc}{Py_complex} +\begin{verbatim} typedef struct { double real; double imag; } +\end{verbatim} + +The \C{} structure which corresponds to the value portion of a Python +complex number object. Most of the functions for dealing with complex +number objects use structures of this type as input or output values, +as appropriate. \end{ctypedesc} \begin{ctypedesc}{PyComplexObject} @@ -2049,7 +2097,7 @@ number type. \end{cvardesc} \begin{cfuncdesc}{int}{PyComplex_Check}{PyObject *p} -returns true if it's argument is a \code{PyComplexObject} +Returns true if its argument is a \code{PyComplexObject}. \end{cfuncdesc} \begin{cfuncdesc}{Py_complex}{_Py_c_sum}{Py_complex, Py_complex} @@ -2111,22 +2159,23 @@ This instance of \code{PyTypeObject} represents the Python file type. \end{cvardesc} \begin{cfuncdesc}{int}{PyFile_Check}{PyObject *p} -returns true if it's argument is a \code{PyFileObject} +Returns true if its argument is a \code{PyFileObject}. \end{cfuncdesc} \begin{cfuncdesc}{PyObject *}{PyFile_FromString}{char *name, char *mode} -creates a new PyFileObject pointing to the file -specified in \code{name} with the mode specified in \code{mode} +Creates a new \code{PyFileObject} pointing to the file +specified in \var{name} with the mode specified in \var{mode}. \end{cfuncdesc} \begin{cfuncdesc}{PyObject *}{PyFile_FromFile}{FILE *fp, char *name, char *mode, int (*close}) -creates a new PyFileObject from the already-open \code{fp}. -The function \code{close} will be called when the file should be closed. +Creates a new \code{PyFileObject} from the already-open \var{fp}. +The function \var{close} will be called when the file should be +closed. \end{cfuncdesc} \begin{cfuncdesc}{FILE *}{PyFile_AsFile}{PyFileObject *p} -returns the file object associated with \code{p} as a \code{FILE *} +Returns the file object associated with \var{p} as a \code{FILE *}. \end{cfuncdesc} \begin{cfuncdesc}{PyStringObject *}{PyFile_GetLine}{PyObject *p, int n} @@ -2134,24 +2183,29 @@ undocumented as yet \end{cfuncdesc} \begin{cfuncdesc}{PyStringObject *}{PyFile_Name}{PyObject *p} -returns the name of the file specified by \code{p} as a -PyStringObject +Returns the name of the file specified by \var{p} as a +\code{PyStringObject}. \end{cfuncdesc} \begin{cfuncdesc}{void}{PyFile_SetBufSize}{PyFileObject *p, int n} -on systems with \code{setvbuf} only +Available on systems with \cfunction{setvbuf()} only. This should +only be called immediately after file object creation. \end{cfuncdesc} \begin{cfuncdesc}{int}{PyFile_SoftSpace}{PyFileObject *p, int newflag} -same as the file object method \code{softspace} +Sets the \code{softspace} attribute of \var{p} to \var{newflag}. +Returns the previosu value. This function clears any errors, and will +return \code{0} as the previous value if the attribute either does not +exist or if there were errors in retrieving it. There is no way to +detect errors from this function, but doing so should not be needed. \end{cfuncdesc} \begin{cfuncdesc}{int}{PyFile_WriteObject}{PyObject *obj, PyFileObject *p} -writes object \code{obj} to file object \code{p} +Writes object \var{obj} to file object \var{p}. \end{cfuncdesc} \begin{cfuncdesc}{int}{PyFile_WriteString}{char *s, PyFileObject *p} -writes string \code{s} to file object \code{p} +Writes string \var{s} to file object \var{p}. \end{cfuncdesc} @@ -2165,36 +2219,36 @@ XXX \begin{cfuncdesc}{void}{Py_Initialize}{} Initialize the Python interpreter. In an application embedding Python, this should be called before using any other Python/C API -functions; with the exception of \code{Py_SetProgramName()}, -\code{PyEval_InitThreads()}, \code{PyEval_ReleaseLock()}, and -\code{PyEval_AcquireLock()}. This initializes the table of loaded -modules (\code{sys.modules}), and creates the fundamental modules -\code{__builtin__}, \code{__main__} and \code{sys}. It also -initializes the module search path (\code{sys.path}). It does not set -\code{sys.argv}; use \code{PySys_SetArgv()} for that. This is a no-op -when called for a second time (without calling \code{Py_Finalize()} -first). There is no return value; it is a fatal error if the -initialization fails. +functions; with the exception of \cfunction{Py_SetProgramName()}, +\cfunction{PyEval_InitThreads()}, \cfunction{PyEval_ReleaseLock()}, +and \cfunction{PyEval_AcquireLock()}. This initializes the table of +loaded modules (\code{sys.modules}), and creates the fundamental +modules \module{__builtin__}, \module{__main__} and \module{sys}. It +also initializes the module search path (\code{sys.path}). It does +not set \code{sys.argv}; use \cfunction{PySys_SetArgv()} for that. +This is a no-op when called for a second time (without calling +\cfunction{Py_Finalize()} first). There is no return value; it is a +fatal error if the initialization fails. \end{cfuncdesc} \begin{cfuncdesc}{int}{Py_IsInitialized}{} \strong{(NEW in 1.5a4!)} Return true (nonzero) when the Python interpreter has been -initialized, false (zero) if not. After \code{Py_Finalize()} is -called, this returns false until \code{Py_Initialize()} is called +initialized, false (zero) if not. After \cfunction{Py_Finalize()} is +called, this returns false until \cfunction{Py_Initialize()} is called again. \end{cfuncdesc} \begin{cfuncdesc}{void}{Py_Finalize}{} \strong{(NEW in 1.5a3!)} -Undo all initializations made by \code{Py_Initialize()} and subsequent -use of Python/C API functions, and destroy all sub-interpreters (see -\code{Py_NewInterpreter()} below) that were created and not yet -destroyed since the last call to \code{Py_Initialize()}. Ideally, -this frees all memory allocated by the Python interpreter. This is a -no-op when called for a second time (without calling -\code{Py_Initialize()} again first). There is no return value; errors -during finalization are ignored. +Undo all initializations made by \cfunction{Py_Initialize()} and +subsequent use of Python/C API functions, and destroy all +sub-interpreters (see \cfunction{Py_NewInterpreter()} below) that were +created and not yet destroyed since the last call to +\cfunction{Py_Initialize()}. Ideally, this frees all memory allocated +by the Python interpreter. This is a no-op when called for a second +time (without calling \cfunction{Py_Initialize()} again first). There +is no return value; errors during finalization are ignored. This function is provided for a number of reasons. An embedding application might want to restart Python without having to restart the @@ -2204,9 +2258,9 @@ free all memory allocated by Python before unloading the DLL. During a hunt for memory leaks in an application a developer might want to free all memory allocated by Python before exiting from the application. -\emph{Bugs and caveats:} The destruction of modules and objects in +\strong{Bugs and caveats:} The destruction of modules and objects in modules is done in random order; this may cause destructors -(\code{__del__} methods) to fail when they depend on other objects +(\method{__del__()} methods) to fail when they depend on other objects (even functions) or modules. Dynamically loaded extension modules loaded by Python are not unloaded. Small amounts of memory allocated by the Python interpreter may not be freed (if you find a leak, please @@ -2214,7 +2268,8 @@ report it). Memory tied up in circular references between objects is not freed. Some memory allocated by extension modules may not be freed. Some extension may not work properly if their initialization routine is called more than once; this can happen if an applcation -calls \code{Py_Initialize()} and \code{Py_Finalize()} more than once. +calls \cfunction{Py_Initialize()} and \cfunction{Py_Finalize()} more +than once. \end{cfuncdesc} \begin{cfuncdesc}{PyThreadState *}{Py_NewInterpreter}{} @@ -2222,8 +2277,8 @@ calls \code{Py_Initialize()} and \code{Py_Finalize()} more than once. Create a new sub-interpreter. This is an (almost) totally separate environment for the execution of Python code. In particular, the new interpreter has separate, independent versions of all imported -modules, including the fundamental modules \code{__builtin__}, -\code{__main__} and \code{sys}. The table of loaded modules +modules, including the fundamental modules \module{__builtin__}, +\module{__main__} and \module{sys}. The table of loaded modules (\code{sys.modules}) and the module search path (\code{sys.path}) are also separate. The new environment has no \code{sys.argv} variable. It has new standard I/O stream file objects \code{sys.stdin}, @@ -2246,16 +2301,16 @@ the first time a particular extension is imported, it is initialized normally, and a (shallow) copy of its module's dictionary is squirreled away. When the same extension is imported by another (sub-)interpreter, a new module is initialized and filled with the -contents of this copy; the extension's \code{init} function is not -called. Note that this is different from what happens when as -extension is imported after the interpreter has been completely -re-initialized by calling \code{Py_Finalize()} and -\code{Py_Initialize()}; in that case, the extension's \code{init} +contents of this copy; the extension's \code{init} function is not +called. Note that this is different from what happens when an +extension is imported after the interpreter has been completely +re-initialized by calling \cfunction{Py_Finalize()} and +\cfunction{Py_Initialize()}; in that case, the extension's \code{init} function \emph{is} called again. -\emph{Bugs and caveats:} Because sub-interpreters (and the main +\strong{Bugs and caveats:} Because sub-interpreters (and the main interpreter) are part of the same process, the insulation between them -isn't perfect -- for example, using low-level file operations like +isn't perfect --- for example, using low-level file operations like \code{os.close()} they can (accidentally or maliciously) affect each other's open files. Because of the way extensions are shared between (sub-)interpreters, some extensions may not work properly; this is @@ -2278,16 +2333,16 @@ discussion of thread states below. When the call returns, the current thread state is \NULL{}. All thread states associated with this interpreted are destroyed. (The global interpreter lock must be held before calling this function and is still held when it returns.) -\code{Py_Finalize()} will destroy all sub-interpreters that haven't +\cfunction{Py_Finalize()} will destroy all sub-interpreters that haven't been explicitly destroyed at that point. \end{cfuncdesc} \begin{cfuncdesc}{void}{Py_SetProgramName}{char *name} \strong{(NEW in 1.5a3!)} -This function should be called before \code{Py_Initialize()} is called +This function should be called before \cfunction{Py_Initialize()} is called for the first time, if it is called at all. It tells the interpreter -the value of the \code{argv[0]} argument to the \code{main()} function -of the program. This is used by \code{Py_GetPath()} and some other +the value of the \code{argv[0]} argument to the \cfunction{main()} function +of the program. This is used by \cfunction{Py_GetPath()} and some other functions below to find the Python run-time libraries relative to the interpreter executable. The default value is \code{"python"}. The argument should point to a zero-terminated character string in static @@ -2297,35 +2352,35 @@ the contents of this storage. \end{cfuncdesc} \begin{cfuncdesc}{char *}{Py_GetProgramName}{} -Return the program name set with \code{Py_SetProgramName()}, or the +Return the program name set with \cfunction{Py_SetProgramName()}, or the default. The returned string points into static storage; the caller should not modify its value. \end{cfuncdesc} \begin{cfuncdesc}{char *}{Py_GetPrefix}{} -Return the ``prefix'' for installed platform-independent files. This +Return the \emph{prefix} for installed platform-independent files. This is derived through a number of complicated rules from the program name -set with \code{Py_SetProgramName()} and some environment variables; +set with \cfunction{Py_SetProgramName()} and some environment variables; for example, if the program name is \code{"/usr/local/bin/python"}, the prefix is \code{"/usr/local"}. The returned string points into static storage; the caller should not modify its value. This corresponds to the \code{prefix} variable in the top-level -\code{Makefile} and the \code{--prefix} argument to the -\code{configure} script at build time. The value is available to +\file{Makefile} and the \code{--prefix} argument to the +\program{configure} script at build time. The value is available to Python code as \code{sys.prefix}. It is only useful on \UNIX{}. See also the next function. \end{cfuncdesc} \begin{cfuncdesc}{char *}{Py_GetExecPrefix}{} -Return the ``exec-prefix'' for installed platform-\emph{de}pendent +Return the \emph{exec-prefix} for installed platform-\emph{de}pendent files. This is derived through a number of complicated rules from the -program name set with \code{Py_SetProgramName()} and some environment +program name set with \cfunction{Py_SetProgramName()} and some environment variables; for example, if the program name is \code{"/usr/local/bin/python"}, the exec-prefix is \code{"/usr/local"}. The returned string points into static storage; the caller should not modify its value. This corresponds to the -\code{exec_prefix} variable in the top-level \code{Makefile} and the -\code{--exec_prefix} argument to the \code{configure} script at build +\code{exec_prefix} variable in the top-level \file{Makefile} and the +\code{--exec_prefix} argument to the \program{configure} script at build time. The value is available to Python code as \code{sys.exec_prefix}. It is only useful on \UNIX{}. @@ -2348,8 +2403,8 @@ meaningless, and set to the empty string. Note that compiled Python bytecode files are platform independent (but not independent from the Python version by which they were compiled!). -System administrators will know how to configure the \code{mount} or -\code{automount} programs to share \code{"/usr/local"} between platforms +System administrators will know how to configure the \program{mount} or +\program{automount} programs to share \code{"/usr/local"} between platforms while having \code{"/usr/local/plat"} be a different filesystem for each platform. \end{cfuncdesc} @@ -2358,7 +2413,7 @@ platform. \strong{(NEW in 1.5a3!)} Return the full program name of the Python executable; this is computed as a side-effect of deriving the default module search path -from the program name (set by \code{Py_SetProgramName()} above). The +from the program name (set by \cfunction{Py_SetProgramName()} above). The returned string points into static storage; the caller should not modify its value. The value is available to Python code as \code{sys.executable}. @@ -2366,7 +2421,7 @@ modify its value. The value is available to Python code as \begin{cfuncdesc}{char *}{Py_GetPath}{} Return the default module search path; this is computed from the -program name (set by \code{Py_SetProgramName()} above) and some +program name (set by \cfunction{Py_SetProgramName()} above) and some environment variables. The returned string consists of a series of directory names separated by a platform dependent delimiter character. The delimiter character is \code{':'} on \UNIX{}, \code{';'} on @@ -2384,7 +2439,7 @@ Return the version of this Python interpreter. This is a string that looks something like \begin{verbatim} -"1.5a3 (#67, Aug 1 1997, 22:34:28) [GCC 2.7.2.2]" +"1.5 (#67, Dec 31 1997, 22:34:28) [GCC 2.7.2.2]" \end{verbatim} The first word (up to the first space character) is the current Python @@ -2418,9 +2473,11 @@ modify its value. The value is available to Python code as the list \begin{cfuncdesc}{const char *}{Py_GetCompiler}{} Return an indication of the compiler used to build the current Python -version, in square brackets, for example +version, in square brackets, for example: -\code{"[GCC 2.7.2.2]"} +\begin{verbatim} +"[GCC 2.7.2.2]" +\end{verbatim} The returned string points into static storage; the caller should not modify its value. The value is available to Python code as part of @@ -2459,25 +2516,25 @@ could end up being incremented only once instead of twice. Therefore, the rule exists that only the thread that has acquired the global interpreter lock may operate on Python objects or call Python/C API functions. In order to support multi-threaded Python programs, -the interpreter regularly release and reacquires the lock -- by +the interpreter regularly release and reacquires the lock --- by default, every ten bytecode instructions (this can be changed with -\code{sys.setcheckinterval()}). The lock is also released and +\function{sys.setcheckinterval()}). The lock is also released and reacquired around potentially blocking I/O operations like reading or writing a file, so that other threads can run while the thread that requests the I/O is waiting for the I/O operation to complete. The Python interpreter needs to keep some bookkeeping information -separate per thread -- for this it uses a data structure called -PyThreadState. This is new in Python 1.5; in earlier versions, such -state was stored in global variables, and switching threads could +separate per thread --- for this it uses a data structure called +\code{PyThreadState}. This is new in Python 1.5; in earlier versions, +such state was stored in global variables, and switching threads could cause problems. In particular, exception handling is now thread safe, -when the application uses \code{sys.exc_info()} to access the exception -last raised in the current thread. +when the application uses \function{sys.exc_info()} to access the +exception last raised in the current thread. There's one global variable left, however: the pointer to the current -PyThreadState structure. While most thread packages have a way to -store ``per-thread global data'', Python's internal platform -independent thread abstraction doesn't support this (yet). Therefore, +\code{PyThreadState} structure. While most thread packages have a way +to store ``per-thread global data'', Python's internal platform +independent thread abstraction doesn't support this yet. Therefore, the current thread state must be manipulated explicitly. This is easy enough in most cases. Most code manipulating the global @@ -2499,11 +2556,11 @@ Py_BEGIN_ALLOW_THREADS Py_END_ALLOW_THREADS \end{verbatim} -The BEGIN macro opens a new block and declares a hidden local -variable; the END macro closes the block. Another advantage of using -these two macros is that when Python is compiled without thread -support, they are defined empty, thus saving the thread state and lock -manipulations. +The \code{Py_BEGIN_ALLOW_THREADS} macro opens a new block and declares +a hidden local variable; the \code{Py_END_ALLOW_THREADS} macro closes +the block. Another advantage of using these two macros is that when +Python is compiled without thread support, they are defined empty, +thus saving the thread state and lock manipulations. When thread support is enabled, the block above expands to the following code: @@ -2532,15 +2589,16 @@ as follows: \end{verbatim} There are some subtle differences; in particular, -\code{PyEval_RestoreThread()} saves and restores the value of the +\cfunction{PyEval_RestoreThread()} saves and restores the value of the global variable \code{errno}, since the lock manipulation does not guarantee that \code{errno} is left alone. Also, when thread support -is disabled, \code{PyEval_SaveThread()} and -\code{PyEval_RestoreThread()} don't manipulate the lock; in this case, -\code{PyEval_ReleaseLock()} and \code{PyEval_AcquireLock()} are not -available. (This is done so that dynamically loaded extensions -compiled with thread support enabled can be loaded by an interpreter -that was compiled with disabled thread support.) +is disabled, \cfunction{PyEval_SaveThread()} and +\cfunction{PyEval_RestoreThread()} don't manipulate the lock; in this +case, \cfunction{PyEval_ReleaseLock()} and +\cfunction{PyEval_AcquireLock()} are not available. This is done so +that dynamically loaded extensions compiled with thread support +enabled can be loaded by an interpreter that was compiled with +disabled thread support. The global interpreter lock is used to protect the pointer to the current thread state. When releasing the lock and saving the thread @@ -2596,12 +2654,14 @@ to this thread's interpreter state. \begin{cfuncdesc}{void}{PyEval_InitThreads}{} Initialize and acquire the global interpreter lock. It should be called in the main thread before creating a second thread or engaging -in any other thread operations such as \code{PyEval_ReleaseLock()} or -\code{PyEval_ReleaseThread(tstate)}. It is not needed before -calling \code{PyEval_SaveThread()} or \code{PyEval_RestoreThread()}. +in any other thread operations such as +\cfunction{PyEval_ReleaseLock()} or +\code{PyEval_ReleaseThread(\var{tstate})}. It is not needed before +calling \cfunction{PyEval_SaveThread()} or +\cfunction{PyEval_RestoreThread()}. This is a no-op when called for a second time. It is safe to call -this function before calling \code{Py_Initialize()}. +this function before calling \cfunction{Py_Initialize()}. When only the main thread exists, no lock operations are needed. This is a common situation (most Python programs do not use threads), and @@ -2609,11 +2669,11 @@ the lock operations slow the interpreter down a bit. Therefore, the lock is not created initially. This situation is equivalent to having acquired the lock: when there is only a single thread, all object accesses are safe. Therefore, when this function initializes the -lock, it also acquires it. Before the Python \code{thread} module +lock, it also acquires it. Before the Python \module{thread} module creates a new thread, knowing that either it has the lock or the lock -hasn't been created yet, it calls \code{PyEval_InitThreads()}. When -this call returns, it is guaranteed that the lock has been created and -that it has acquired it. +hasn't been created yet, it calls \cfunction{PyEval_InitThreads()}. +When this call returns, it is guaranteed that the lock has been +created and that it has acquired it. It is \strong{not} safe to call this function when it is unknown which thread (if any) currently has the global interpreter lock. @@ -2634,8 +2694,7 @@ compile time. \strong{(NEW in 1.5a3!)} Release the global interpreter lock. The lock must have been created earlier. This function is not available when thread support is -disabled at -compile time. +disabled at compile time. \end{cfuncdesc} \begin{cfuncdesc}{void}{PyEval_AcquireThread}{PyThreadState *tstate} @@ -2644,8 +2703,7 @@ Acquire the global interpreter lock and then set the current thread state to \var{tstate}, which should not be \NULL{}. The lock must have been created earlier. If this thread already has the lock, deadlock ensues. This function is not available when thread support -is disabled at -compile time. +is disabled at compile time. \end{cfuncdesc} \begin{cfuncdesc}{void}{PyEval_ReleaseThread}{PyThreadState *tstate} @@ -2654,9 +2712,9 @@ Reset the current thread state to \NULL{} and release the global interpreter lock. The lock must have been created earlier and must be held by the current thread. The \var{tstate} argument, which must not be \NULL{}, is only used to check that it represents the current -thread state -- if it isn't, a fatal error is reported. This function -is not available when thread support is disabled at -compile time. +thread state --- if it isn't, a fatal error is reported. This +function is not available when thread support is disabled at compile +time. \end{cfuncdesc} \begin{cfuncdesc}{PyThreadState *}{PyEval_SaveThread}{} @@ -2682,7 +2740,7 @@ time.) % XXX These aren't really C types, but the ctypedesc macro is the simplest! \begin{ctypedesc}{Py_BEGIN_ALLOW_THREADS} This macro expands to -\code{\{ PyThreadState *_save; _save = PyEval_SaveThread();}. +\samp{\{ PyThreadState *_save; _save = PyEval_SaveThread();}. Note that it contains an opening brace; it must be matched with a following \code{Py_END_ALLOW_THREADS} macro. See above for further discussion of this macro. It is a no-op when thread support is @@ -2691,7 +2749,7 @@ disabled at compile time. \begin{ctypedesc}{Py_END_ALLOW_THREADS} This macro expands to -\code{PyEval_RestoreThread(_save); \} }. +\samp{PyEval_RestoreThread(_save); \}}. Note that it contains a closing brace; it must be matched with an earlier \code{Py_BEGIN_ALLOW_THREADS} macro. See above for further discussion of this macro. It is a no-op when thread support is @@ -2699,14 +2757,14 @@ disabled at compile time. \end{ctypedesc} \begin{ctypedesc}{Py_BEGIN_BLOCK_THREADS} -This macro expands to \code{PyEval_RestoreThread(_save);} i.e. it +This macro expands to \samp{PyEval_RestoreThread(_save);} i.e. it is equivalent to \code{Py_END_ALLOW_THREADS} without the closing brace. It is a no-op when thread support is disabled at compile time. \end{ctypedesc} \begin{ctypedesc}{Py_BEGIN_UNBLOCK_THREADS} -This macro expands to \code{_save = PyEval_SaveThread();} i.e. it is +This macro expands to \samp{_save = PyEval_SaveThread();} i.e. it is equivalent to \code{Py_BEGIN_ALLOW_THREADS} without the opening brace and variable declaration. It is a no-op when thread support is disabled at compile time. @@ -2729,7 +2787,7 @@ lock must be held. \begin{cfuncdesc}{void}{PyInterpreterState_Delete}{PyInterpreterState *interp} Destroy an interpreter state object. The interpreter lock need not be held. The interpreter state must have been reset with a previous -call to \code{PyInterpreterState_Clear()}. +call to \cfunction{PyInterpreterState_Clear()}. \end{cfuncdesc} \begin{cfuncdesc}{PyThreadState *}{PyThreadState_New}{PyInterpreterState *interp} @@ -2745,7 +2803,7 @@ must be held. \begin{cfuncdesc}{void}{PyThreadState_Delete}{PyThreadState *tstate} Destroy a thread state object. The interpreter lock need not be held. The thread state must have been reset with a previous -call to \code{PyThreadState_Clear()}. +call to \cfunction{PyThreadState_Clear()}. \end{cfuncdesc} \begin{cfuncdesc}{PyThreadState *}{PyThreadState_Get}{} @@ -2761,9 +2819,20 @@ must be held. \end{cfuncdesc} -\section{Defining New Object Types} +\chapter{Defining New Object Types} + +\begin{cfuncdesc}{PyObject *}{_PyObject_New}{PyTypeObject *type} +\end{cfuncdesc} + +\begin{cfuncdesc}{PyObject *}{_PyObject_NewVar}{PyTypeObject *type, int size} +\end{cfuncdesc} + +\begin{cfuncdesc}{TYPE}{_PyObject_NEW}{TYPE, PyTypeObject *} +\end{cfuncdesc} + +\begin{cfuncdesc}{TYPE}{_PyObject_NEW_VAR}{TYPE, PyTypeObject *, int size} +\end{cfuncdesc} -XXX To be done: PyObject, PyVarObject @@ -2794,25 +2863,6 @@ Py*_Check Py_None, _Py_NoneStruct -_PyObject_New, _PyObject_NewVar - -PyObject_NEW, PyObject_NEW_VAR - - -\chapter{Defining New Object Types} - -\begin{cfuncdesc}{PyObject *}{_PyObject_New}{PyTypeObject *type} -\end{cfuncdesc} - -\begin{cfuncdesc}{PyObject *}{_PyObject_NewVar}{PyTypeObject *type, int size} -\end{cfuncdesc} - -\begin{cfuncdesc}{TYPE}{_PyObject_NEW}{TYPE, PyTypeObject *} -\end{cfuncdesc} - -\begin{cfuncdesc}{TYPE}{_PyObject_NEW_VAR}{TYPE, PyTypeObject *, int size} -\end{cfuncdesc} - \chapter{Debugging} |