Alastair Houghton wrote:
(The current groups() method *doesn't* match those expectations, incidentally. I know I've been tripped up in the past because it didn't include the full match as element 0.)
that's because there is no "group 0" in a regular expression; that's just a historical API convenience thing. groups are numbered from 1 and upwards, and "groups()" returns all the actual groups.
What's more, I think it will be confusing for Python newbies because they'll see someone doing
m[3]
and assume that m is a list-like object, then complain when things like
for match in m: print match
that'll work, of course, which might be confusing for people who think they understand how for-in works but don't ;)
or
m[3:4]
fail to do what they expect.
the problem with slicing is that people may 1) expect a slice to return a new object *of the same type* (which opens up a *gigantic* can of worms, both on the implementation level and on the wtf-is-this-thing- really level), and 2) expect things like [::-1] to work, which opens up another can of worms. I prefer the "If the implementation is easy to explain, it may be a good idea." design principle over "can of worms" design principle. </F>