Re: [Python-Dev] replace on empty strings
On 5/24/06, Fredrik Lundh [EMAIL PROTECTED] wrote:
so, which one is correct ?
Python 2.4.3
.replace(, a)
''
u.replace(u, ua)
u'a'
Since 'x'.replace('', 'a') and u'x'.replace('', u'a') return 'axa' and
u'axa', respectively, I conclude that the unicode version is correct
and the 8-bit string version is an anomaly.
--
--Guido van Rossum (home page: http://www.python.org/~guido/)
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Re: [Python-Dev] replace on empty strings
[/F] so, which one is correct ? Python 2.4.3 .replace(, a) '' u.replace(u, ua) u'a' [Greg Ewing] Probably there shouldn't be any correct in this case, i.e. the result of replacing an empty string should be undefined (because any string contains infinitely many empty substrings). Where are they? For a string s, I count s[0:0], s[1:1], ..., s[len(s):len(s)], or len(s)+1 empty substrings in all. While str and unicode `replace` currently disagree about that when len(s)==0, they agree when len(s)0: .replace(, A) 'A A' u .replace(, A) u'A A' +0 on raising an exception if you try. I'd be +1, except the idea that there are len(s)+1 empty substrings in a string is pretty much ubiquitous: in True u in u True .index() 0 u.index(u) 0 .rindex() 1 u .rindex(u) 1 .count() 1 u.count(u) 1 .count() 2 u .count(u) 2 So the current str.replace really is an oddball. ___ Python-Dev mailing list Python-Dev@python.org http://mail.python.org/mailman/listinfo/python-dev Unsubscribe: http://mail.python.org/mailman/options/python-dev/archive%40mail-archive.com
Re: [Python-Dev] replace on empty strings
On 5/24/06, Greg Ewing [EMAIL PROTECTED] wrote: Fredrik Lundh wrote: so, which one is correct ? Python 2.4.3 .replace(, a) '' u.replace(u, ua) u'a' Probably there shouldn't be any correct in this case, i.e. the result of replacing an empty string should be undefined (because any string contains infinitely many empty substrings). No. That's what older versions of Python did, and it was changed to the current behavior, except someone screwed up the edge case for 8-bit strings. -- --Guido van Rossum (home page: http://www.python.org/~guido/) ___ Python-Dev mailing list Python-Dev@python.org http://mail.python.org/mailman/listinfo/python-dev Unsubscribe: http://mail.python.org/mailman/options/python-dev/archive%40mail-archive.com
