[Python-Dev] map, filter, zip in future_builtins

[Guido van Rossum]

On Tue, Mar 18, 2008 at 3:54 PM, David Wolever <wolever at cs.toronto.edu> wrote:
> I'm working on #2171 -- putting map, filter, zip in 2.6's
>  future_builtins.
>  It has been suggested that it would be simplest to just return
>  itertools.(imap, izip, ifilter), which is what py3k/Python/
>  bltinmodule.c, revision 61356 did.
>
>  The advantage of this is that it's really easy and the behaviour
>  seems to be identical.
>  The disadvantage is that the two aren't identical:
>   >>> type(map(lambda x: x, [1, 2, 3]))  # Python 3
>  <type 'map'>
>   >>> type(map(lambda x: x, [1, 2, 3])) == map
>  True
>
>   >>> type(map(lambda x: x, [1, 2, 3])) # Python 2.6, with the patch
>  <type 'itertools.imap'>
>   >>> type(map(lambda x: x, [1, 2, 3])) == map
>  False
>
>  Recommendations?

Doesn't strike me as a terrible problem.

Why is the latter == failing? What's the different between
type(map(...)) and map?

-- 
--Guido van Rossum (home page: http://www.python.org/~guido/)