[Python-ideas] An iterable version of find/index for strings?

[Tom Schumm]

Should Python strings (and byte arrays, and other iterables for that matter) 
have an iterator form of find/rfind (or index/rindex)? I've found myself 
wanting one on occasion, and having more iterable things seems to be the 
direction the language is moving.

Currently, looping over the instances of a substring in a larger string is a 
bit awkward. You have to keep track of where you are, and you either have have 
to watch for the -1 sentinel value or catch the ValueError. A "for idx in ..." 
construction would just be cleaner. You could use re.finditer, but a string 
method seems a more lightweight/efficient/obvious.

The best name I can think of would be "finditer()" like re.finditer(). Using 
"ifind" (like izip) would be confusing, because it could be mistaken for case-
insensitive find. I thought of "iterfind" like the old dict.iteritems, and 
ElementTree.iterfind but "iterrfind" (iterable rfind) is unattractive. I also 
think "find" is a more obvious verb than "index".

I've got a simple Python implementation on gist:
https://gist.github.com/fwiffo/5233377

It includes an option to include overlapping instences, which may not be 
necessary (it's not present in e.g. re.finditer).

I could imagine it as a method on str/unicode/bytes/list/tuple objects, or 
maybe as a function in itertools.

-- 
Tom Schumm
http://www.fwiffo.com/