On Sat, Jul 20, 2013 at 11:04 AM, Devyn Collier Johnson <devyncjohn...@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
