[Python-Dev] other "magic strings" issues

Guido van Rossum guido at python.org
Fri Nov 7 17:49:31 EST 2003

> I guess the tests should be faster, yes, but I would still want _iterables_
> for ascii_*  and digits.

Why?  It's not like you're going to save much space by not creating a
string of 52 bytes.

> One issue with allowing "if char in string.letters:" is that these
> days this will not raise if the alleged 'char' is more than one
> character -- it will give True for (e.g.) 'ab', False for (e.g.) 
> 'foobar', since it tests _substrings_.


> So, maybe, str.letters and friends should be iterables which also
> implement a __contains__ method that raises some error with helpful
> information about using .iswhatever() instead -- that's assuming we
> want people NOT to test with "if char in str.letters:".  If we DO
> want people to test that way, then I think str.letters should
> _still_ have __contains__, but specifically one to optimize speed in
> this case (if supported it should be just as fast as the
> .is... method -- which as Skip reminds us may in turn need
> optimization...).

Hm.  The iterable idea seems overblown for something as simple as

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

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