diff options
Diffstat (limited to 'Doc/ext')
| -rw-r--r-- | Doc/ext/ext.tex | 54 |
1 files changed, 30 insertions, 24 deletions
diff --git a/Doc/ext/ext.tex b/Doc/ext/ext.tex index 0532212..454e767 100644 --- a/Doc/ext/ext.tex +++ b/Doc/ext/ext.tex @@ -85,7 +85,7 @@ as follows: >>> status = spam.system("ls -l") \end{verbatim} -Begin by creating a file \samp{spammodule.c}. (In general, if a +Begin by creating a file \file{spammodule.c}. (In general, if a module is called \samp{spam}, the \C{} file containing its implementation is called \file{spammodule.c}; if the module name is very long, like \samp{spammify}, the module name can be just \file{spammify.c}.) @@ -120,6 +120,7 @@ spam_system(self, args) { char *command; int sts; + if (!PyArg_ParseTuple(args, "s", &command)) return NULL; sts = system(command); @@ -265,6 +266,7 @@ void initspam() { PyObject *m, *d; + m = Py_InitModule("spam", SpamMethods); d = PyModule_GetDict(m); SpamError = PyErr_NewException("spam.error", NULL, NULL); @@ -334,8 +336,8 @@ returning \ctype{void}), the corresponding Python function must return \end{verbatim} \cdata{Py_None} is the \C{} name for the special Python object -\code{None}. It is a genuine Python object (not a \NULL{} -pointer, which means ``error'' in most contexts, as we have seen). +\code{None}. It is a genuine Python object rather than a \NULL{} +pointer, which means ``error'' in most contexts, as we have seen. \section{The Module's Method Table and Initialization Function} @@ -357,7 +359,7 @@ static PyMethodDef SpamMethods[] = { Note the third entry (\samp{METH_VARARGS}). This is a flag telling the interpreter the calling convention to be used for the \C{} function. It should normally always be \samp{METH_VARARGS} or -\samp{METH_VARARGS | METH_KEYWORDS}; a value of \samp{0} means that an +\samp{METH_VARARGS | METH_KEYWORDS}; a value of \code{0} means that an obsolete variant of \cfunction{PyArg_ParseTuple()} is used. When using only \samp{METH_VARARGS}, the function should expect @@ -402,15 +404,15 @@ doesn't need to check for errors. There are two more things to do before you can use your new extension: compiling and linking it with the Python system. If you use dynamic loading, the details depend on the style of dynamic loading your -system uses; see the chapter on Dynamic Loading for more info about -this. +system uses; see the chapter ``Dynamic Loading'' for more information +about this. If you can't use dynamic loading, or if you want to make your module a permanent part of the Python interpreter, you will have to change the configuration setup and rebuild the interpreter. Luckily, this is very simple: just place your file (\file{spammodule.c} for example) in the \file{Modules} directory, add a line to the file -\file{Modules/Setup} describing your file: +\file{Modules/Setup.local} describing your file: \begin{verbatim} spam spammodule.o @@ -418,12 +420,12 @@ spam spammodule.o and rebuild the interpreter by running \program{make} in the toplevel directory. You can also run \program{make} in the \file{Modules} -subdirectory, but then you must first rebuilt the \file{Makefile} +subdirectory, but then you must first rebuild \file{Makefile} there by running `\program{make} Makefile'. (This is necessary each time you change the \file{Setup} file.) If your module requires additional libraries to link with, these can -be listed on the line in the \file{Setup} file as well, for instance: +be listed on the line in the configuration file as well, for instance: \begin{verbatim} spam spammodule.o -lX11 @@ -747,9 +749,9 @@ Some example calls: int left, top, right, bottom, h, v; ok = PyArg_ParseTuple(args, "((ii)(ii))(ii)", &left, &top, &right, &bottom, &h, &v); - /* A rectangle and a point */ - /* Possible Python call: - f(((0, 0), (400, 300)), (10, 10)) */ + /* A rectangle and a point */ + /* Possible Python call: + f(((0, 0), (400, 300)), (10, 10)) */ } { @@ -784,7 +786,8 @@ arguments! Keyword parameters passed in which are not present in the \var{kwlist} will cause \exception{TypeError} to be raised. Here is an example module which uses keywords, based on an example by -Geoff Philbrick (\email{philbrick@hks.com}): +Geoff Philbrick (\email{philbrick@hks.com}):% +\index{Philbrick, Geoff} \begin{verbatim} #include <stdio.h> @@ -1110,7 +1113,7 @@ owner. There are exactly two important exceptions to this rule: \cfunction{PyTuple_SetItem()} and \cfunction{PyList_SetItem()}. These functions take over ownership of the item passed to them --- even if they fail! (Note that \cfunction{PyDict_SetItem()} and friends don't -take over ownership --- they are ``normal''.) +take over ownership --- they are ``normal.'') When a \C{} function is called from Python, it borrows references to its arguments from the caller. The caller owns a reference to the object, @@ -1138,6 +1141,7 @@ reference to a list item. For instance: \begin{verbatim} bug(PyObject *list) { PyObject *item = PyList_GetItem(list, 0); + PyList_SetItem(list, 1, PyInt_FromLong(0L)); PyObject_Print(item, stdout, 0); /* BUG! */ } @@ -1171,6 +1175,7 @@ function reads: \begin{verbatim} no_bug(PyObject *list) { PyObject *item = PyList_GetItem(list, 0); + Py_INCREF(item); PyList_SetItem(list, 1, PyInt_FromLong(0L)); PyObject_Print(item, stdout, 0); @@ -1206,7 +1211,7 @@ bug(PyObject *list) { \subsection{NULL Pointers} \label{nullPointers} -In general, functions that take object references as arguments don't +In general, functions that take object references as arguments do not expect you to pass them \NULL{} pointers, and will dump core (or cause later core dumps) if you do so. Functions that return object references generally return \NULL{} only to indicate that an @@ -1220,7 +1225,7 @@ when a pointer that may be \NULL{} is received, e.g.\ from \cfunction{malloc()} or from a function that may raise an exception. The macros \cfunction{Py_INCREF()} and \cfunction{Py_DECREF()} -don't check for \NULL{} pointers --- however, their variants +do not check for \NULL{} pointers --- however, their variants \cfunction{Py_XINCREF()} and \cfunction{Py_XDECREF()} do. The macros for checking for a particular object type @@ -1329,13 +1334,14 @@ loading. \label{sharedlibs} The following systems support dynamic loading using shared libraries: -SunOS 4; Solaris 2; SGI IRIX 5 (but not SGI IRIX 4!); and probably all -systems derived from SVR4, or at least those SVR4 derivatives that -support shared libraries (are there any that don't?). +SunOS 4; Solaris 2; SGI IRIX 5 (but not SGI IRIX 4!), Linux, FreeBSD, +NetBSD; and probably all systems derived from SVR4, or at least those +SVR4 derivatives that support shared libraries (are there any that +don't?). You don't need to do anything to configure dynamic loading on these systems --- the \file{configure} detects the presence of the -\file{<dlfcn.h>} header file and automatically configures dynamic +\code{<dlfcn.h>} header file and automatically configures dynamic loading. \subsection{SGI IRIX 4 Dynamic Loading} @@ -1348,12 +1354,12 @@ work right away so I gave up trying to support it.) Before you build Python, you first need to fetch and build the \code{dl} package written by Jack Jansen. This is available by -anonymous ftp from \url{ftp://ftp.cwi.nl/pub/dynload}, file +anonymous ftp from \url{ftp://ftp.cwi.nl/pub/dynload/}, file \file{dl-1.6.tar.Z}. (The version number may change.) Follow the instructions in the package's \file{README} file to build it. Once you have built \code{dl}, you can configure Python to use it. To -this end, you run the \file{configure} script with the option +this end, you run the \program{configure} script with the option \code{--with-dl=\var{directory}} where \var{directory} is the absolute pathname of the \code{dl} directory. @@ -1417,7 +1423,7 @@ contain the options \samp{-I\$(PYTHONTOP) -I\$(PYTHONTOP)/Include}. You must link the \file{.o} file to produce a shared library. This is done using a special invocation of the \UNIX{} loader/linker, -\emph{ld}(1). Unfortunately the invocation differs slightly per +\manpage{ld}{1}. Unfortunately the invocation differs slightly per system. On SunOS 4, use @@ -1451,7 +1457,7 @@ along the Python module search path. \label{irixLinking} \strong{IMPORTANT:} You must compile your extension module with the -additional \C{} flag \samp{-G0} (or \samp{-G 0}). This instruct the +additional \C{} flag \samp{-G0} (or \samp{-G 0}). This instructs the assembler to generate position-independent code. You don't need to link the resulting \file{spammodule.o} file; just |