On Oct 13, 2019, at 02:38, Steve Jorgensen <ste...@stevej.name> wrote:
>
> Note that I'm new to this system, so I'm not sure if this will format
> correctly or whether I'll be able to edit it afterward to format it properly
> if not. Fingers crossed.
>
> Examples:
> import re
> from collections import Sequence
>
> # Equivalent of re.compile(r'b.d').search(<str>)
> re.compile(r'b.d') in 'abcdef' # -> <_sre.SRE_Match object; span=(1, 4),
> match='bcd'>
> re.compile(r'b.d') in 'xyz' # -> None
>
> # Equivalent of isinstance([1, 2], Sequence)
> [1, 2] in Sequence # -> True
>
> class BrightColorsMeta(type):
> def __rin__(self, other):
> other.startswith('bright ')
>
> class BrightColors(metaclass=BrightColorsMeta): pass
>
> 'red' in BrightColors # -> False
> 'bright blue' in BrightColors # -> True
That method already exists, it’s just called `__contains__`. Many types already
customize this; you even get it for free from mixins like
`collections.abc.Sequence`.
Also, I’m not sure why you want `BrightColors` to be a class here. It doesn’t
have any instances, or any other class behavior. It’s sort of like an
open-ended `Enum`, but without any of the actual enum functionality. But
anyway, you could write this today if you want it.
I think what you want for the other examples is to add an `__rcontains__`
method, so instead of `x in y` meaning `y.__contains__(x)`, it means either
`y.__contains__(x)` or `x.__rcontains__(y)` depending on some rule that you
have to define. Should it be the same rules as `__radd__`? You probably want to
work through all of the cases for those rules with some example types.
_______________________________________________
Python-ideas mailing list -- python-ideas@python.org
To unsubscribe send an email to python-ideas-le...@python.org
https://mail.python.org/mailman3/lists/python-ideas.python.org/
Message archived at
https://mail.python.org/archives/list/python-ideas@python.org/message/LNGP2CIV2B7YJ2GSU5MO4KTQOB3VHU67/
Code of Conduct: http://python.org/psf/codeofconduct/
