From: Jason R. Coombs Date: Sat, 3 Dec 2011 13:24:21 +0000 (-0500) Subject: Issue #12666: Added section about map changes. X-Git-Tag: v3.3.0a1~694^2 X-Git-Url: https://granicus.if.org/sourcecode?a=commitdiff_plain;h=a90e364ea5c301e76e67e23e2162f4fa8066a6f3;p=python Issue #12666: Added section about map changes. --- diff --git a/Doc/howto/pyporting.rst b/Doc/howto/pyporting.rst index 309f3f7a3a..df0d299f4a 100644 --- a/Doc/howto/pyporting.rst +++ b/Doc/howto/pyporting.rst @@ -505,6 +505,18 @@ Otherwise it might very well be worth your time and effort to port your tests to :mod:`unittest`. +Update `map` for imbalanced input sequences +''''''''''''''''''''''''''''''''''''''''''' + +With Python 2, `map` would pad input sequences of unequal length with +`None` values, returning a sequence as long as the longest input sequence. + +With Python 3, if the input sequences to `map` are of unequal length, `map` +will stop at the termination of the shortest of the sequences. For full +compatibility with `map` from Python 2.x, also wrap the sequences in +:func:`itertools.zip_longest`, e.g. ``map(func, *sequences)`` becomes +``list(map(func, itertools.zip_longest(*sequences)))``. + Eliminate ``-3`` Warnings -------------------------