[Python-checkins] python/dist/src/Doc/lib liboperator.tex, 1.29, 1.30

[rhettinger at users.sourceforge.net]

Update of /cvsroot/python/python/dist/src/Doc/lib
In directory sc8-pr-cvs1:/tmp/cvs-serv29352/Doc/lib

Modified Files:
	liboperator.tex 
Log Message:
As discussed on python-dev, added two extractor functions to the
operator module.



Index: liboperator.tex
===================================================================
RCS file: /cvsroot/python/python/dist/src/Doc/lib/liboperator.tex,v
retrieving revision 1.29
retrieving revision 1.30
diff -C2 -d -r1.29 -r1.30
*** liboperator.tex	27 Nov 2003 19:48:03 -0000	1.29
--- liboperator.tex	1 Dec 2003 13:18:39 -0000	1.30
***************
*** 301,304 ****
--- 301,337 ----
  
  
+ The \module{operator} module also defines tools for generalized attribute
+ and item lookups.  These are useful for making fast field extractors
+ as arguments for \function{map()}, \method{list.sort()},
+ \method{itertools.groupby()}, or other functions that expect a
+ function argument.
+ 
+ \begin{funcdesc}{attrgetter}{attr}
+ Return a callable object that fetches \var{attr} from its operand.
+ After, \samp{f=attrgetter('name')}, the call \samp{f(b)} returns
+ \samp{b.name}.
+ \versionadded{2.4}
+ \end{funcdesc}
+     
+ \begin{funcdesc}{itemgetter}{item}
+ Return a callable object that fetches \var{item} from its operand.
+ After, \samp{f=itemgetter(2)}, the call \samp{f(b)} returns
+ \samp{b[2]}.
+ \versionadded{2.4}
+ \end{funcdesc}
+ 
+ Examples:
+                 
+ \begin{verbatim}
+ >>> from operator import *
+ >>> inventory = [('apple', 3), ('banana', 2), ('pear', 5), ('orange', 1)]
+ >>> getcount = itemgetter(1)
+ >>> map(getcount, inventory)
+ [3, 2, 5, 1]
+ >>> list.sorted(inventory, key=getcount)
+ [('orange', 1), ('banana', 2), ('apple', 3), ('pear', 5)]
+ \end{verbatim}
+                 
+ 
  \subsection{Mapping Operators to Functions \label{operator-map}}