Update of /cvsroot/python/python/dist/src/Doc/lib In directory sc8-pr-cvs1.sourceforge.net:/tmp/cvs-serv14403/Doc/lib Modified Files: lib.tex Added Files: libfunctional.tex Log Message: SF patch #941881: PEP 309 Implementation (Partial Function Application). Combined efforts of many including Peter Harris, Hye-Shik Chang, Martin v. Löwis, Nick Coghlan, Paul Moore, and Raymond Hettinger. --- NEW FILE: libfunctional.tex --- \section{\module{functional} --- Higher order functions and operations on callable objects.} \declaremodule{standard}{functional} % standard library, in Python \moduleauthor{Peter Harris}{scav@blueyonder.co.uk} \moduleauthor{Raymond Hettinger}{python@rcn.com} \sectionauthor{Peter Harris}{scav@blueyonder.co.uk} \modulesynopsis{Higher-order functions and operations on callable objects.} The \module{functional} module is for higher-order functions: functions that act on or return other functions. In general, any callable object can be treated as a function for the purposes of this module. The \module{functional} module defines the following function: \begin{funcdesc}{partial}{func\optional{,*args}\optional{, **keywords}} Return a new \class{partial} object which when called will behave like \var{func} called with the positional arguments \var{args} and keyword arguments \var{keywords}. If more arguments are supplied to the call, they are appended to \var{args}. If additional keyword arguments are supplied, they extend and override \var{keywords}. Roughly equivalent to: \begin{verbatim} def partial(func, *args, **keywords): def newfunc(*fargs, **fkeywords): newkeywords = keywords.copy() newkeywords.update(fkeywords) return func(*(args + fargs), **newkeywords) newfunc.func = func newfunc.args = args newfunc.keywords = keywords return newfunc \end{verbatim} The \function{partial} is used for partial function application which ``freezes'' some portion of a function's arguments and/or keywords resulting in an new object with a simplified signature. For example, \function{partial} can be used to create a callable that behaves like the \function{int} function where the \var{base} argument defaults to two: \begin{verbatim} >>> basetwo = partial(int, base=2) >>> basetwo('10010') 18 \end{verbatim} \end{funcdesc} \subsection{\class{partial} Objects \label{partial-objects}} \class{partial} objects are callable objects created by \function{partial()}. They have three read-only attributes: \begin{memberdesc}[callable]{func}{} A callable object or function. Calls to the \class{partial} object will be forwarded to \member{func} with new arguments and keywords. \end{memberdesc} \begin{memberdesc}[tuple]{args}{} The leftmost positional arguments that will be prepended to the positional arguments provided to a \class{partial} object call. \end{memberdesc} \begin{memberdesc}[dict]{keywords}{} The keyword arguments that will be supplied when the \class{partial} object is called. \end{memberdesc} Index: lib.tex =================================================================== RCS file: /cvsroot/python/python/dist/src/Doc/lib/lib.tex,v retrieving revision 1.237 retrieving revision 1.238 diff -u -d -r1.237 -r1.238 --- lib.tex 23 Jan 2005 09:27:23 -0000 1.237 +++ lib.tex 28 Feb 2005 19:39:23 -0000 1.238 @@ -132,6 +132,7 @@ \input{libarray} \input{libsets} \input{libitertools} +\input{libfunctional} \input{libcfgparser} \input{libfileinput} \input{libcalendar}