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diff --git a/Doc/tut/glossary.tex b/Doc/tut/glossary.tex index 008b774..0c9cfc5 100644 --- a/Doc/tut/glossary.tex +++ b/Doc/tut/glossary.tex @@ -6,84 +6,97 @@ \begin{description} \index{...} -\item[...]{The typical Python prompt of the interactive shell when entering -code for an indented code block.} +\item[\code{.\code{.}.}] +The typical Python prompt of the interactive shell when entering code +for an indented code block. \index{>>>} -\item[>>>]{The typical Python prompt of the interactive shell. Often seen -for code examples that can be tried right away in the interpreter.} +\item[\code{>\code{>}>}] +The typical Python prompt of the interactive shell. Often seen for +code examples that can be tried right away in the interpreter. \index{__slots__} -\item[__slots__]{A declaration inside a \emph{new-style class} that saves -memory by pre-declaring space for instance attributes and eliminating -instance dictionaries. Though popular, the technique is somewhat tricky to -get right and is best reserved for rare cases where there are large numbers -of instances in a memory critical application.} +\item[__slots__] +A declaration inside a \emph{new-style class} that saves memory by +pre-declaring space for instance attributes and eliminating instance +dictionaries. Though popular, the technique is somewhat tricky to get +right and is best reserved for rare cases where there are large +numbers of instances in a memory critical application. \index{BDFL} -\item[BDFL]{Benevolent Dictator For Life, a.k.a. \ulink{Guido van -Rossum}{http://www.python.org/~guido/}, Python's creator.} +\item[BDFL] +Benevolent Dictator For Life, a.k.a. \ulink{Guido van +Rossum}{http://www.python.org/~guido/}, Python's creator. \index{byte code} -\item[byte code]{The internal representation of a Python program in the -interpreter. The byte code is also cached in the \code{.pyc} and -{}\code{.pyo} files so that executing the same file is faster the second -time (compilation from source to byte code can be saved). This -"intermediate language" is said to run on a "virtual machine" that calls the -subroutines corresponding to each bytecode.} +\item[byte code] +The internal representation of a Python program in the interpreter. +The byte code is also cached in the \code{.pyc} and \code{.pyo} +files so that executing the same file is faster the second time +(compilation from source to byte code can be saved). This +\emph{intermediate language} is said to run on a \emph{virtual +machine} that calls the subroutines corresponding to each bytecode. \index{classic class} -\item[classic class]{Any class which does not inherit from \class{object}. -See new-style class.} +\item[classic class] +Any class which does not inherit from \class{object}. See +\emph{new-style class}. \index{coercion} -\item[coercion]{Converting data from one type to another. For example, -{}\code{int(3.15)} coerces the floating point number to the integer, \code{3}. -Most mathematical operations have rules for coercing their arguments to a common -type. For instance, adding \code{3 + 4.5}, causes the integer \code{3} to be -coerced to be a float \code{3.0} before adding to \code{4.5} resulting in the -float \code{7.5}.} +\item[coercion] +Converting data from one type to another. For example, +{}\code{int(3.15)} coerces the floating point number to the integer, +{}\code{3}. Most mathematical operations have rules for coercing +their arguments to a common type. For instance, adding \code{3 + +4.5}, causes the integer \code{3} to be coerced to be a float +{}\code{3.0} before adding to \code{4.5} resulting in the float +{}\code{7.5}. \index{descriptor} -\item[descriptor]{Any object that defines the methods \method{__get__()}, -\method{__set__()}, or \method{__delete__()}. When a class attribute is a -descriptor, its special binding behavior is triggered upon attribute lookup. -Normally, writing {}\var{a.b} looks up the object \var{b} in the class -dictionary for \var{a}, but if \var{b} is a descriptor, the defined method -gets called. Understanding descriptors is a key to a deep understanding of -Python because they are the basis for many features including functions, -methods, properties, class methods, static methods, and reference to super -classes.} +\item[descriptor] +Any \emph{new-style} object that defines the methods +{}\method{__get__()}, \method{__set__()}, or \method{__delete__()}. +When a class attribute is a descriptor, its special binding behavior +is triggered upon attribute lookup. Normally, writing \var{a.b} looks +up the object \var{b} in the class dictionary for \var{a}, but if +{}\var{b} is a descriptor, the defined method gets called. +Understanding descriptors is a key to a deep understanding of Python +because they are the basis for many features including functions, +methods, properties, class methods, static methods, and reference to +super classes. \index{dictionary} -\item[dictionary]{An associative array, where arbitrary keys are mapped to -values. The use of \class{dict} much resembles that for \class{list}, but -the keys can be any object with a \function{__hash__} function, not just -integers starting from zero. Called a hash in Perl.} +\item[dictionary] +An associative array, where arbitrary keys are mapped to values. The +use of \class{dict} much resembles that for \class{list}, but the keys +can be any object with a \method{__hash__()} function, not just +integers starting from zero. Called a hash in Perl. \index{EAFP} -\item[EAFP]{Easier to ask for forgiveness than permission. This common -Python coding style assumes the existence of valid keys or attributes and -catches exceptions if the assumption proves false. This clean and fast -style is characterized by the presence of many \keyword{try} and -{}\keyword{except} statements. The technique contrasts with the \emph{LBYL} -style that is common in many other languages such as C.} +\item[EAFP] +Easier to ask for forgiveness than permission. This common Python +coding style assumes the existence of valid keys or attributes and +catches exceptions if the assumption proves false. This clean and +fast style is characterized by the presence of many \keyword{try} and +{}\keyword{except} statements. The technique contrasts with the +{}\emph{LBYL} style that is common in many other languages such as C. \index{__future__} -\item[__future__]{A pseudo module which programmers can use to enable -new language features which are not compatible with the current interpreter. -For example, the expression \code{11 / 4} currently evaluates to \code{2}. -If the module in which it is executed had enabled emph{true division} by -executing:} +\item[__future__] +A pseudo module which programmers can use to enable new language +features which are not compatible with the current interpreter. For +example, the expression \code{11 / 4} currently evaluates to \code{2}. +If the module in which it is executed had enabled emph{true division} +by executing: \begin{verbatim} from __future__ import division \end{verbatim} -the expression \code{11 / 4} would evaluate to \code{2.75}. By actually -importing the \module{__future__} module and evaluating its variables, you -can see when a new feature was first added to the language and when it will -become the default: +the expression \code{11 / 4} would evaluate to \code{2.75}. By +actually importing the \refmodule[future]{__future__} module and +evaluating its variables, you can see when a new feature was first +added to the language and when it will become the default: \begin{verbatim} >>> import __future__ @@ -92,177 +105,205 @@ _Feature((2, 2, 0, 'alpha', 2), (3, 0, 0, 'alpha', 0), 8192) \end{verbatim} \index{generator} -\item[generator]{A function that returns an iterator. It looks like a -normal function except that the \keyword{yield} keyword is used instead of +\item[generator] +A function that returns an iterator. It looks like a normal function +except that the \keyword{yield} keyword is used instead of {}\keyword{return}. Generator functions often contain one or more -{}\keyword{for} or \keyword{while} loops that \keyword{yield} elements back to -the caller. The function execution is stopped at the \keyword{yield} keyword -(returning the result) and is resumed there when the next element is -requested by calling the \function{next()} method of the returned iterator.} +{}\keyword{for} or \keyword{while} loops that \keyword{yield} elements +back to the caller. The function execution is stopped at the +{}\keyword{yield} keyword (returning the result) and is resumed there +when the next element is requested by calling the \method{next()} +method of the returned iterator. \index{GIL} -\item[GIL]{See \emph{global interpreter lock}.} +\item[GIL] +See \emph{global interpreter lock}. \index{global interpreter lock} -\item[global interpreter lock]{the lock used by Python threads to assure -that only one thread can be run at a time. This simplifies Python by -assuring that no two processes can access the same memory at the same time. -Locking the entire interpreter makes it easier for the interpreter to be +\item[global interpreter lock] +The lock used by Python threads to assure that only one thread can be +run at a time. This simplifies Python by assuring that no two +processes can access the same memory at the same time. Locking the +entire interpreter makes it easier for the interpreter to be multi-threaded, at the expense of some parallelism on multi-processor -machines. Efforts have been made in the past to create a "free-threaded" -interpreter (one which locks shared data at a much finer granularity), but -performance suffered in the common single-processor case.} +machines. Efforts have been made in the past to create a +"free-threaded" interpreter (one which locks shared data at a much +finer granularity), but performance suffered in the common +single-processor case. \index{IDLE} -\item[IDLE]{an Integrated Development Environment for Python. IDLE is a +\item[IDLE] +An Integrated Development Environment for Python. IDLE is a basic editor and interpreter environment that ships with the standard distribution of Python. Good for beginners, it also serves as clear example code for those wanting to implement a moderately -sophisticated, multi-platform GUI application.} +sophisticated, multi-platform GUI application. \index{immutable} -\item[immutable]{A object with fixed value. Immutable objects are numbers, -strings or tuples (and more). Such an object cannot be altered. A new object +\item[immutable] +A object with fixed value. Immutable objects are numbers, strings or +tuples (and more). Such an object cannot be altered. A new object has to be created if a different value has to be stored. They play an -important role in places where a constant hash value is needed. For example -as a key in a dictionary.} +important role in places where a constant hash value is needed. For +example as a key in a dictionary. \index{integer division} -\item[integer division]{Mathematical division discarding any remainder. For -example, the expression \code{11 / 4} currently evaluates to \code{2} in -contrast to the \code{2.75} returned by float division. Also called -\emph{floor division}. When dividing two integers the outcome will always be -another integer (having the floor function applied to it). However, if one -of the operands is another numeric type (such as a \class{float}), the result -will be coerced (see \emph{coercion}) to a common type. For example, a integer -divided by a float will result in a float value, possibly with a decimal -fraction. Integer division can be forced by using the \code{//} operator -instead of the \code{/} operator. -See also, \emph{__future__}.} +\item[integer division] +Mathematical division discarding any remainder. For example, the +expression \code{11 / 4} currently evaluates to \code{2} in contrast +to the \code{2.75} returned by float division. Also called +{}\emph{floor division}. When dividing two integers the outcome will +always be another integer (having the floor function applied to it). +However, if one of the operands is another numeric type (such as a +{}\class{float}), the result will be coerced (see \emph{coercion}) to +a common type. For example, a integer divided by a float will result +in a float value, possibly with a decimal fraction. Integer division +can be forced by using the \code{//} operator instead of the \code{/} +operator. See also \emph{__future__}. \index{interactive} -\item[interactive]{Python has an interactive interpreter which means that -you can try out things and directly see its result. Just launch -{}\code{python} with no arguments (possibly by selecting it from your -computer's main menu). It is a very powerful way to test out new ideas or -inspect modules and packages (remember \code{help(x)}).} +\item[interactive] +Python has an interactive interpreter which means that you can try out +things and directly see its result. Just launch \code{python} with no +arguments (possibly by selecting it from your computer's main menu). +It is a very powerful way to test out new ideas or inspect modules and +packages (remember \code{help(x)}). \index{interpreted} -\item[interpreted]{Python is an interpreted language, opposed to a compiled -one. This means that the source files can be run right away without first -making an executable which is then run. Interpreted languages typically have +\item[interpreted] +Python is an interpreted language, opposed to a compiled one. This +means that the source files can be run right away without first making +an executable which is then run. Interpreted languages typically have a shorter development/debug cycle than compiled ones. See also -{}\emph{interactive}.} +{}\emph{interactive}. \index{iterable} -\item[iterable]{A container object capable of returning its members one at a -time. Examples of iterables include all sequence types (such as\class{list}, +\item[iterable] +A container object capable of returning its members one at a time. +Examples of iterables include all sequence types (such as\class{list}, {}\class{str}, and \class{tuple}) and some non-sequence types like -{}\class{dict} and \class{file} and objects of any classes you define with -an \method{__iter__} or \function{__getitem__} method. Iterables can be -used in a \keyword{for} loop and in many other places where a sequence is -needed (\function{zip}, \function{map}, ...). When an iterable object is -passed as an argument to the builtin function \function{iter()}, it returns -an iterator for the object. This iterator is good for one pass over the set -of values. When using iterables, it is usually not necessary to call -{}\function{iter()} or deal with iterator objects yourself - the \code{for} -statement does that automatically for you, creating a temporary unnamed -variable to hold the iterator for the duration of the loop. See also -\emph{iterator}, \emph{sequence} and \emph{generator}.} +{}\class{dict} and \class{file} and objects of any classes you define +with an \method{__iter__()} or \method{__getitem__()} method. Iterables +can be used in a \keyword{for} loop and in many other places where a +sequence is needed (\function{zip()}, \function{map()}, ...). When an +iterable object is passed as an argument to the builtin function +{}\function{iter()}, it returns an iterator for the object. This +iterator is good for one pass over the set of values. When using +iterables, it is usually not necessary to call \function{iter()} or +deal with iterator objects yourself---the \code{for} statement does +that automatically for you, creating a temporary unnamed variable to +hold the iterator for the duration of the loop. See also +{}\emph{iterator}, \emph{sequence}, and \emph{generator}. \index{iterator} -\item[iterator]{An object representing a stream of data. Repeated calls to -the iterator's \function{next()} method return successive items in the +\item[iterator] +An object representing a stream of data. Repeated calls to the +iterator's \method{next()} method return successive items in the stream. When no more data is available a \exception{StopIteration} -exception is raised instead. At this point, the iterator object is exhausted -and any further calls to its \function{next()} method just raise -{}\exception{StopIteration} again. Iterators are required to have an -{}\function{__iter__()} method that returns the iterator object itself so -every iterator is also iterable and may be used in most places where other -iterables are accepted. One notable exception is code that attempts -multiple iteration passes. A container object (such as a \class{list}) -produces a fresh new iterator each time you pass it to the \function{iter()} -function or use it in a \function{for} loop. Attempting this with an iterator -will just return the same exhausted iterator object from the second iteration -pass, making it appear like an empty container.} +exception is raised instead. At this point, the iterator object is +exhausted and any further calls to its \method{next()} method just +raise \exception{StopIteration} again. Iterators are required to have +an \method{__iter__()} method that returns the iterator object +itself so every iterator is also iterable and may be used in most +places where other iterables are accepted. One notable exception is +code that attempts multiple iteration passes. A container object +(such as a \class{list}) produces a fresh new iterator each time you +pass it to the \function{iter()} function or use it in a +{}\keyword{for} loop. Attempting this with an iterator will just +return the same exhausted iterator object from the second iteration +pass, making it appear like an empty container. \index{list comprehension} -\item[list comprehension]{A compact way to process all or a subset of elements -in a sequence and return a list with the results. \code{result = ["0x\%02x" +\item[list comprehension] +A compact way to process all or a subset of elements in a sequence and +return a list with the results. \code{result = ["0x\%02x" \% x for x in range(256) if x \% 2 == 0]} generates a list of strings containing hex numbers (0x..) that are even and in the range from 0 to 255. The \keyword{if} clause is optional. If omitted, all elements in -{}\code{range(256)} are processed in that case.} +{}\code{range(256)} are processed in that case. \index{mapping} -\item[mapping]{A container object (such as \class{dict}) that supports -arbitrary key lookups using the special method \function{__getitem__()}.} +\item[mapping] +A container object (such as \class{dict}) that supports arbitrary key +lookups using the special method \method{__getitem__()}. \index{metaclass} -\item[metaclass]{The class of a class. Class definitions create a class -name, a class dictionary, and a list of base classes. The metaclass is -responsible for taking those three arguments and creating the class. Most -object oriented programming languages provide a default implementation. -What makes Python special is that it is possible to create custom -metaclasses. Most users never need this tool, but when the need arises, -metaclasses can provide powerful, elegant solutions. They have been used -for logging attribute access, adding thread-safety, tracking object -creation, implementing singletons, and many other tasks.} +\item[metaclass] +The class of a class. Class definitions create a class name, a class +dictionary, and a list of base classes. The metaclass is responsible +for taking those three arguments and creating the class. Most object +oriented programming languages provide a default implementation. What +makes Python special is that it is possible to create custom +metaclasses. Most users never need this tool, but when the need +arises, metaclasses can provide powerful, elegant solutions. They +have been used for logging attribute access, adding thread-safety, +tracking object creation, implementing singletons, and many other +tasks. \index{LBYL} -\item[LBYL]{Look before you leap. This coding style explicitly tests for -pre-conditions before making calls or lookups. This style contrasts with -the \emph{EAFP} approach and is characterized the presence of many -{}\keyword{if} statements.} +\item[LBYL] +Look before you leap. This coding style explicitly tests for +pre-conditions before making calls or lookups. This style contrasts +with the \emph{EAFP} approach and is characterized the presence of +many \keyword{if} statements. \index{mutable} -\item[mutable]{Mutable objects can change their value but keep their -\function{id()}. See also immutable.} +\item[mutable] +Mutable objects can change their value but keep their \function{id()}. +See also \emph{immutable}. \index{namespace} -\item[namespace]{The place where a variable is stored. Namespaces are -implemented as dictionary. There is the local, global and builtins -namespace and the nested namespaces in objects (in methods). Namespaces -support modularity by preventing naming conflicts. For instance, the -functions \function{__builtins__.open()} and \function{os.open()} are -distinguished by their namespaces. Namespaces also aid readability and -maintainability by making it clear which modules implement a function. For -instance, writing \function{random.seed()} or \function{itertools.izip()} -makes it clear that those functions are implemented by the \module{random} -and \module{itertools} modules respectively.} +\item[namespace] +The place where a variable is stored. Namespaces are implemented as +dictionary. There is the local, global and builtins namespace and the +nested namespaces in objects (in methods). Namespaces support +modularity by preventing naming conflicts. For instance, the +functions \function{__builtin__.open()} and \function{os.open()} are +distinguished by their namespaces. Namespaces also aid readability +and maintainability by making it clear which modules implement a +function. For instance, writing \function{random.seed()} or +{}\function{itertools.izip()} makes it clear that those functions are +implemented by the \refmodule{random} and \refmodule{itertools} +modules respectively. \index{nested scope} -\item[nested scope]{The ability to refer to a variable in an enclosing -definition. For instance, a function defined inside another function can -refer to variables in the outer function. Note that nested scopes work only +\item[nested scope] +The ability to refer to a variable in an enclosing definition. For +instance, a function defined inside another function can refer to +variables in the outer function. Note that nested scopes work only for reference and not for assignment which will always write to the -innermost scope. In contrast, local variables both read and write in the -innermost scope. Likewise, global variables read and write to the global -namespace.} +innermost scope. In contrast, local variables both read and write in +the innermost scope. Likewise, global variables read and write to the +global namespace. \index{new-style class} -\item[new-style class]{Any class that inherits from \class{object}. This -includes all built-in types like \class{list} and \class{dict}. Only -new-style classes can use Python's newer, versatile features like -{}\var{__slots__}, descriptors, properties, \var{__getattribute__}, class -methods, and static methods.} +\item[new-style class] +Any class that inherits from \class{object}. This includes all +built-in types like \class{list} and \class{dict}. Only new-style +classes can use Python's newer, versatile features like +{}\var{__slots__}, descriptors, properties, +\method{__getattribute__()}, class methods, and static methods. \index{Python3000} -\item[Python3000]{A mythical python release, allowed not to be backward -compatible, with telepathic interface.} +\item[Python3000] +A mythical python release, allowed not to be backward compatible, with +telepathic interface. \index{sequence} -\item[sequence]{An \emph{iterable} which supports efficient element access using -integer indices via the \function{__getitem__} and \function{__len()__} -special methods. Some builtin sequence types are \class{list}, \class{str}, -{}\class{tuple}, and \class{unicode}. Note that \class{dict} also supports -{}\function{__getitem__} and \function{__len__}, but is considered a mapping -rather than a sequence because the lookups use arbitrary \emph{immutable} keys -rather than integers.} +\item[sequence] +An \emph{iterable} which supports efficient element access using +integer indices via the \method{__getitem__()} and +{}\method{__len__()} special methods. Some built-in sequence types +are \class{list}, \class{str}, \class{tuple}, and \class{unicode}. +Note that \class{dict} also supports \method{__getitem__()} and +{}\method{__len__()}, but is considered a mapping rather than a +sequence because the lookups use arbitrary \emph{immutable} keys +rather than integers. \index{Zen of Python} -\item[Zen of Python]{listing of Python design principles and philosophies -that are helpful in understanding and using the language. The listing can -be found by typing \code{import this} at the interactive prompt.} +\item[Zen of Python] +Listing of Python design principles and philosophies that are helpful +in understanding and using the language. The listing can be found by +typing \code{import this} at the interactive prompt. \end{description} |