Re: [Python-Dev] future_builtins (was: Backporting PEP 3127 to trunk)

On Sat, Feb 23, 2008 at 8:06 AM, Guido van Rossum wrote:

I don't think a -3 warning for oct or hex would do any good.

I do think map() and filter() should issue a warning under -3 when the first arg is None. (Or does 2to3 detect this now?)

2to3 does detect that: it will turn map(None, foo) into list(foo).

On Sat, Feb 23, 2008 at 6:06 AM, Eric Smith wrote:

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Georg Brandl wrote:

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Eric Smith schrieb:

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I wonder if, in order to change the behavior of various built-in functions, it wouldn't be easier to be able to write

from future_builtins import oct, hex # and who knows what else This makes sense to me, especially if we have a 2to3 fixer which removes

Guido van Rossum wrote: this line. I'll work on implementing future_builtins.

Will the future map and filter also belong there (and if they are imported from future_builtins, 2to3 won't put a list() around them)?

I can certainly do the mechanics of adding the new versions of map and filter to future_builtins, if it's seen as desirable.

Maybe we could have 2to3 not put list() around map and filter, if there's been an import of future_builtins. I realize that there are pathological cases where 2to3 doesn't know that a usage of map or filter would really be the generator version from future_builtins, as opposed to the actual list-producing builtins. But would it be good enough to take an import of future_builtins as a hint that the author was aware that 2to3 wasn't going to change map and filter?

Still an open issue in my mind is adding a -3 warning to oct and hex, and now conceivably map and filter. Would that be going too far?

Eric. _______________________________________________ Python-Dev mailing list Python-Dev@python.org http://mail.python.org/mailman/listinfo/python-dev Unsubscribe: http://mail.python.org/mailman/options/python-dev/guido%40python.org

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

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