[Python-checkins] python/dist/src/Doc/lib libitertools.tex, 1.21, 1.22

Wed Nov 12 09:32:28 EST 2003

Update of /cvsroot/python/python/dist/src/Doc/lib
In directory sc8-pr-cvs1:/tmp/cvs-serv16547/Doc/lib
Modified Files:
	libitertools.tex 
Log Message:
Improve the implementation of itertools.tee().
Formerly, underlying queue was implemented in terms of two lists. The
new queue is a series of singly-linked fixed length lists.
The new implementation runs much faster, supports multi-way tees, and
allows tees of tees without additional memory costs.
The root ideas for this structure were contributed by Andrew Koenig
and Guido van Rossum.
Index: libitertools.tex
===================================================================
RCS file: /cvsroot/python/python/dist/src/Doc/lib/libitertools.tex,v
retrieving revision 1.21
retrieving revision 1.22
diff -C2 -d -r1.21 -r1.22
*** libitertools.tex	26 Oct 2003 15:34:50 -0000	1.21
--- libitertools.tex	12 Nov 2003 14:32:25 -0000	1.22
***************
*** 282,288 ****
 \end{funcdesc}

! \begin{funcdesc}{tee}{iterable}
! Return two independent iterators from a single iterable.
! Equivalent to:

 \begin{verbatim}
--- 282,288 ----
 \end{funcdesc}

! \begin{funcdesc}{tee}{iterable\optional{, n=2}}
! Return \var{n} independent iterators from a single iterable.
! The case where \var{n} is two is equivalent to:

 \begin{verbatim}
***************
*** 300,303 ****
--- 300,307 ----
 \end{verbatim}

+ Note, once \function{tee()} has made a split, the original \var{iterable}
+ should not be used anywhere else; otherwise, the \var{iterable} could get
+ advanced without the tee objects being informed.
+ 
 Note, this member of the toolkit may require significant auxiliary
 storage (depending on how much temporary data needs to be stored).
***************
*** 409,413 ****
 "s -> (s0,s1), (s1,s2), (s2, s3), ..."
 a, b = tee(iterable)
! return izip(a, islice(b, 1, None))

 \end{verbatim}
--- 413,421 ----
 "s -> (s0,s1), (s1,s2), (s2, s3), ..."
 a, b = tee(iterable)
! try:
! b.next()
! except StopIteration:
! pass
! return izip(a, b)

 \end{verbatim}