Ron Garret wrote:
I'm trying to split a CamelCase string into its constituent components. This kind of works:

re.split('[a-z][A-Z]', 'fooBarBaz')
['fo', 'a', 'az']

but it consumes the boundary characters. To fix this I tried using lookahead and lookbehind patterns instead, but it doesn't work:

re.split('((?<=[a-z])(?=[A-Z]))', 'fooBarBaz')
['fooBarBaz']

However, it does seem to work with findall:

re.findall('(?<=[a-z])(?=[A-Z])', 'fooBarBaz')
['', '']

So the regular expression seems to be doing the Right Thing. Is this a bug in re.split, or am I missing something?

(BTW, I tried looking at the source code for the re module, but I could not find the relevant code. re.split calls sre_compile.compile().split, but the string 'split' does not appear in sre_compile.py. So where does this method come from?)

I'm using Python2.5.

I, amongst others, think it's a bug (or 'misfeature'); Guido thinks it
might be intentional, but changing it could break some existing code.
You could do this instead:

>>> re.sub('(?<=[a-z])(?=[A-Z])', '@', 'fooBarBaz').split('@')
['foo', 'Bar', 'Baz']
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