Share Code Tips

David Hutto dwightdhutto at gmail.com
Sat Jul 20 05:42:00 CEST 2013


Just use an explanatory user tip that states it should be case sensitive,
just like with most sites, or apps.


On Fri, Jul 19, 2013 at 9:13 PM, Chris Angelico <rosuav at gmail.com> wrote:

> On Sat, Jul 20, 2013 at 11:04 AM, Devyn Collier Johnson
> <devyncjohnson at gmail.com> wrote:
> >
> > On 07/19/2013 07:09 PM, Dave Angel wrote:
> >>
> >> On 07/19/2013 06:08 PM, Devyn Collier Johnson wrote:
> >>>
> >>>
> >>> On 07/19/2013 01:59 PM, Steven D'Aprano wrote:
> >>
> >>
> >>      <snip>
> >>>
> >>>
> >>> As for the case-insensitive if-statements, most code uses Latin
> letters.
> >>> Making a case-insensitive-international if-statement would be
> >>> interesting. I can tackle that later. For now, I only wanted to take
> >>> care of Latin letters. I hope to figure something out for all
> characters.
> >>>
> >>
> >> Once Steven gave you the answer, what's to figure out?  You simply use
> >> casefold() instead of lower().  The only constraint is it's 3.3 and
> later,
> >> so you can't use it for anything earlier.
> >>
> >> http://docs.python.org/3.3/library/stdtypes.html#str.casefold
> >>
> >> """
> >> str.casefold()
> >> Return a casefolded copy of the string. Casefolded strings may be used
> for
> >> caseless matching.
> >>
> >> Casefolding is similar to lowercasing but more aggressive because it is
> >> intended to remove all case distinctions in a string. For example, the
> >> German lowercase letter 'ß' is equivalent to "ss". Since it is already
> >> lowercase, lower() would do nothing to 'ß'; casefold() converts it to
> "ss".
> >>
> >> The casefolding algorithm is described in section 3.13 of the Unicode
> >> Standard.
> >>
> >> New in version 3.3.
> >> """
> >>
> > Chris Angelico said that casefold is not perfect. In the future, I want
> to
> > make the perfect international-case-insensitive if-statement. For now, my
> > code only supports a limited range of characters. Even with casefold, I
> will
> > have some issues as Chris Angelico mentioned. Also, "ß" is not really the
> > same as "ss".
>
> Well, casefold is about as good as it's ever going to be, but that's
> because "the perfect international-case-insensitive comparison" is a
> fundamentally impossible goal. Your last sentence hints as to why;
> there is no simple way to compare strings containing those characters,
> because the correct treatment varies according to context.
>
> Your two best options are: Be case sensitive (and then you need only
> worry about composition and combining characters and all those
> nightmares - the ones you have to worry about either way), or use
> casefold(). Of those, I prefer the first, because it's safer; the
> second is also a good option.
>
> ChrisA
> --
> http://mail.python.org/mailman/listinfo/python-list
>



-- 
Best Regards,
David Hutto
*CEO:* *http://www.hitwebdevelopment.com*
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