[issue7203] fixer for map(None, ...) needs to consider multi-argument case

[Florian Mayer]

Florian Mayer  added the comment:

When could this possibly be wrong, if I may ask?

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[issue7203] fixer for map(None, ...) needs to consider multi-argument case

[Benjamin Peterson]

Benjamin Peterson  added the comment:

2009/10/27 Florian Mayer :
>
> Florian Mayer  added the comment:
>
> At least converting
>
> map(None, a, b, ...)
>
> to
>
> map(lambda *xs: xs, a, b, ...)

Well, since that's not always correct, we should not translate to it.

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[issue7203] fixer for map(None, ...) needs to consider multi-argument case

[Florian Mayer]

Florian Mayer  added the comment:

At least converting

map(None, a, b, ...)

to

map(lambda *xs: xs, a, b, ...)

I can understand if you prefer not to add the itertools.zip_longest
workaround, although that would be the correct translation, of course.

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[issue7203] fixer for map(None, ...) needs to consider multi-argument case

[Benjamin Peterson]

Benjamin Peterson  added the comment:

2009/10/27 Florian Mayer :
>
> Florian Mayer  added the comment:
>
> I dare to disagree on this being an adequate fix. Request to reopen.

What would you prefer?

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[issue7203] fixer for map(None, ...) needs to consider multi-argument case

[Florian Mayer]

Florian Mayer  added the comment:

I dare to disagree on this being an adequate fix. Request to reopen.

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[issue7203] fixer for map(None, ...) needs to consider multi-argument case

[Benjamin Peterson]

Benjamin Peterson  added the comment:

Fixed in r75734.

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nosy: +benjamin.peterson
resolution:  -> fixed
status: open -> closed

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[issue7203] fixer for map(None, ...) needs to consider multi-argument case

[Florian Mayer]

Florian Mayer  added the comment:

A full fix would be

list(map(fun, *zip(*itertools.zip_longest(a, b, ...

and if fun is None

list(map(lambda *xs: xs, *zip(*itertools.zip_longest(a, b, ...

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[issue7203] fixer for map(None, ...) needs to consider multi-argument case

[Florian Mayer]

Changes by Florian Mayer :


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nosy: +segfaulthunter

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[issue7203] fixer for map(None, ...) needs to consider multi-argument case

[Georg Brandl]

New submission from Georg Brandl :

Currently, ``map(None, a)`` is recognized and converted to ``list(a)``
which is correct but quite useless.

``map(None, a, b, ...)`` is not treated specially.  An approximate
translation would be ``map(lambda *xs: xs, a, b, ...)`` which however
doesn't take into account that the new map cuts after the shortest
sequence instead of "filling up" the shorter ones with Nones.

That should probably produce a warning.

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components: 2to3 (2.x to 3.0 conversion tool)
messages: 94455
nosy: georg.brandl
priority: high
severity: normal
stage: needs patch
status: open
title: fixer for map(None, ...) needs to consider multi-argument case
type: behavior
versions: Python 3.1, Python 3.2

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