[Python-Dev] Re: string.find() again (was Re: timsort for jython)

[Inyeol Lee]

Guido> I think we've argued about '' in 'abc' long enough.  Tim has failed to
Guido> convince me, so '' in 'abc' returns True.  Barry has checked it all
Guido> in.

I'm Inyeol Lee, happy python user. I checked other string methods and
re functions.

1. most of them assume null character between normal characters and
   at the start/end of string;

   'abc'.count('') -> 4
   'abc'.endswith('') -> 1
   'abc'.find('') -> 0
   'abc'.index('') -> 0
   'abc'.rfind('') -> 3
   'abc'.rindex('') -> 3
   'abc'.startswith('') -> 1

   re.search('', 'abc').span() -> (0, 0)
   re.match('', 'abc').span() -> (0, 0)
   re.findall('', 'abc') -> ['', '', '', '']
   re.sub('', '_', 'abc') -> '_a_b_c_'
   re.subn('', '_', 'abc') -> ('_a_b_c_', 4)

2. some of them generate exception;

   '' in 'abc'
   'abc'.replace('', '_')
   'abc'.split('')

3. one of them ignores empty match;

   re.split('', 'abc') -> ['abc']

(couldn't test re.finditer but it seems to be the same as re.findall.)


Since '' in 'abc' now returns True, How about changing 'abc'.replace('')
to generate '_a_b_c_', too? It is consistent with re.sub()/subn() and the
cost for change is similar to '' in 'abc' case.

Inyeol Lee