Case-insensitive string equality

[Serhiy Storchaka]

31.08.17 15:49, Steve D'Aprano пише:
> On Thu, 31 Aug 2017 05:51 pm, Serhiy Storchaka wrote:
>> 31.08.17 10:10, Steven D'Aprano пише:
>>> (iii) Not every two line function needs to be in the standard library.
>>> Just add this to the top of every module:
>>>
>>> def equal(s, t):
>>>       return s.casefold() == t.casefold()
>>
>> This is my answer.
>>
>>> Unsolved problems:
>>>
>>> This proposal doesn't help with sets and dicts, list.index and the `in`
>>> operator either.
>>
>> This is the end of the discussion.
> 
> Your answer of an equal() function doesn't help with sets and dicts either.

See rejected issue18986 [1], PEP 455 [2] and corresponding mailing lists 
discussions. The conclusion was that the need of such collections is low 
and the problems that they are purposed to solve can be solved with 
normal dict (as they are solved now).

> So I guess we're stuck with no good standard answer:
> 
> - the easy two-line function doesn't even come close to solving the problem
>    of case-insensitive string operations;

It is not clear what is your problem exactly. The easy one-line function 
solves the problem of testing case-insensitive string equality. Regular 
expressions solve the problem of case-insensitive searching a position 
of a substring. If you asked a solution that magically prevent people 
from making simple programming mistakes, there is no such solution.

[1] https://bugs.python.org/issue18986
[2] https://www.python.org/dev/peps/pep-0455/