Mercurial > cpython-lru_cache-weakref
diff Doc/lib/libstdtypes.tex @ 24459:189eb6fa9ded legacy-trunk
Added new footnote about list.sort() stability. Repaired footnote about
using sort() with comparison functions (it made reference to the non-
existent "builtin-in function sort()").
BTW, I changed list.sort's docstring to contain the word "stable" -- the
easiest way to tell whether a particular Python version's sort *is* stable
is to look for "stable" in the docstring. I'm not sure whether to
advertise this <wink>.
| author | Tim Peters <tim.peters@gmail.com> |
|---|---|
| date | Thu, 01 Aug 2002 03:10:45 +0000 |
| parents | 62f4b45b05fd |
| children | 12e146171f3d |
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--- a/Doc/lib/libstdtypes.tex Thu Aug 01 02:34:51 2002 +0000 +++ b/Doc/lib/libstdtypes.tex Thu Aug 01 03:10:45 2002 +0000 @@ -901,7 +901,7 @@ \lineiii{\var{s}.reverse()} {reverses the items of \var{s} in place}{(6)} \lineiii{\var{s}.sort(\optional{\var{cmpfunc}})} - {sort the items of \var{s} in place}{(6), (7)} + {sort the items of \var{s} in place}{(6), (7), (8)} \end{tableiii} \indexiv{operations on}{mutable}{sequence}{types} \indexiii{operations on}{sequence}{types} @@ -947,10 +947,18 @@ the first argument is considered smaller than, equal to, or larger than the second argument. Note that this slows the sorting process down considerably; e.g. to sort a list in reverse order it is much - faster to use calls to the methods \method{sort()} and - \method{reverse()} than to use the built-in function - \function{sort()} with a comparison function that reverses the + faster to call method \method{sort()} followed by + \method{reverse()} than to use method + \method{sort()} with a comparison function that reverses the ordering of the elements. + +\item[(8)] Whether the \method{sort()} method is stable is not defined by + the language (a sort is stable if it guarantees not to change the + relative order of elements that compare equal). In the C + implementation of Python, sorts were stable only by accident through + Python 2.2. The C implementation of Python 2.3 introduced a stable + \method{sort()} method, but code that intends to be portable across + implementations and versions must not rely on stability. \end{description}
