[Python-Dev] [NPERS] Re: a feature i'd like to see in python #2: indexing of match objects

[Michael Urman]

On 12/6/06, Josiah Carlson <jcarlson at uci.edu> wrote:
> Special cases aren't special enough to break the rules.

Sure, but where is this rule that would be broken? I've seen it
invoked, but I've never felt it myself. I seriously thought of slicing
as returning a list of elements per range(start,stop,skip), with the
special case being str (and then unicode followed)'s type
preservation.

This is done because a list of characters is a pain to work with in
most contexts, so there's an implicit ''.join on the list. And because
assuming that the joined string is the desired result, it's much
faster to have just built it in the first place. A pure practicality
beats purity argument.

We both arrive at the same place in that we have a model describing
the behavior for list/str/unicode, but they're different models when
extended outside.

Now that I see the connection you're drawing between your argument and
the paper, I don't believe it's directly inspired by the paper. I read
the paper to say those who could create and work with a set of rules,
could learn to work with the correct rules. Consistency in Python
makes things easier on everyone because there's less to remember, not
because it makes us better learners of the skills necessary for
programming well. The arguments I saw in the paper only addressed the
second point.
-- 
Michael Urman  http://www.tortall.net/mu/blog