[Python-Dev] Re: pre-PEP: Complete, Structured Regular Expression Group Matching

[Erik Heneryd]

Mike Coleman wrote:
> Paul Moore <pf_moore at yahoo.co.uk> writes:

>>The only other comment I have is that the semantics seem pretty
>>complex - I think that in practice, they do more or less what you want
>>them to, but the description is pretty obscure.

I'd say that is probably a warning flag, but I don't know, at the same 
time it looks like it could be kind of useful.

>>And although I can see that the error return has some value, I suspect that
>>it might actually complicate real use.
> 
> 
> Someone else suggested throwing an exception instead, which I'm now leaning in
> favor of, too.

Exceptions are the way to go.  You should get what you ask for, or a 
heads up.  Errors should never pass silently.

> 
> 
>>A suggestion - would it be possible to implement re.structmatch as a
>>pure Python prototype, to thrash out some of the usability questions?
>>If the function appears valuable in such a form, arguing for
>>incorporation into the re module would be a lot easier.
> 
> 
> I suspect that in this case a pure Python implementation might actually be a
> lot harder than implementing it as a C patch.  This is because so much of the
> work is already done in the current re module; the C patch would probably not
> be that big.  In order to do it in Python I'd end up reimplementing re.match
> in Python, which I wouldn't look forward to.

I hacked up a Python prototype, mostly as a challenge.  It's brittle and 
it's ugly, but it kind of works.  Though, if /F says it would require a 
major rewrite of the C-engine, that's probably true... <wink>


Erik

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