[Python-ideas] is in operator

[George Sakkis]

On 9/26/07, Mathias Panzenböck <grosser.meister.morti at gmx.net> wrote:
>
> Sometimes I want to compare a "pointer" to more then one others. The "in"
> operator
> would be handy, but it uses the "==" operator instead of the "is"
> operator. So a "is
> in" operator would be nice. Though I don't know how easy it is for a
> newbie to see
> what does what.
>
> # This:
> if x is in (a, b, c):
>         ...
>
> # would be equivalent to this:
> if x is a or x is b or x is c:
>         ...
>
> # And of course there should be a "is not in" operator, too:
> if x is not in (a, b, c):
>         ...
>
> # this would be equivalent to tis:
> if x is not a and x is not b and x is not c:
>         ...
>
>
> Hmmm, maybe a way to apply some kind of comparison between a value and
> more other
> values would be better. But that already exists, so screw this msg:
>
> if any(x is y for y in (a, b, c)):
>         ...
>
> if all(x is not y for y in (a, b, c)):



Or in a more obfuscated way:

import operator as op
from itertools import imap
from functools import partial

if any(imap(partial(op.is_,x), (a, b, c))):
        ...

if all(imap(partial(op.is_not,x), (a, b, c))):
     ...


George
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