[Python-Dev] PEP 246, redux

[Michel Pelletier]

On Monday 10 January 2005 09:58 am, python-dev-request at python.org wrote:

> Message: 3
> Date: Mon, 10 Jan 2005 07:46:39 -0800
> From: Guido van Rossum <gvanrossum at gmail.com>
> Subject: Re: [Python-Dev] PEP 246, redux
> To: Alex Martelli <aleax at aleax.it>
> Cc: "Clark C.Evans" <cce at clarkevans.com>, Python Dev
> 	<python-dev at python.org>
> Message-ID: <ca471dc2050110074614f5edc3 at mail.gmail.com>
> Content-Type: text/plain; charset=US-ASCII
>
> > I had been promising to rewrite PEP 246 to incorporate the last several
> > years' worth of discussions &c about it, and Guido's recent "stop the
> > flames" artima blog post finally pushed me to complete the work.
> > Feedback is of course welcome, so I thought I had better repost it
> > here, rather than relying on would-be commenters to get it from CVS...
>
> Thanks for doing this, Alex! I yet have to read the whole thing [will
> attempt do so later today] but the few snippets I caught make me feel
> this is a big step forward.

Me too!  I didn't realize it the first time 246 came around how important 
adaptation was and how interfaces just aren't as useful without it.

>
> I'm wondering if someone could do a similar thing for PEP 245,
> interfaces syntax? Alex hinted that it's a couple of rounds behind the
> developments in Zope and Twisted. 

Nothing implements 245, which is just about the syntax, I intended to write 
another PEP describing an implementation, at the time Jim's original 
straw-man; which I'm glad I didn't do as it would have been a waste of time.  
Had I written that document, then it would be a copule of rounds behind Zope 
and Twisted.  But as it stands now nothing need be based on 245.

> I'm personally not keen on needing 
> *two* new keywords (interface and implements) so I hope that whoever
> does the rewrite could add a section on the advantages and
> disadvantages of the 'implements' keyword (my simplistic alternative
> proposal is to simply include interfaces in the list of bases in the
> class statement; the metaclass can then sort it out).

I like implements, but any spelling works for me.  "implements" strikes me as 
an elegant counterpart to "interface" and risks minimal breakage.  Can we 
still import and say "implements()" for b/w compatibility and for those of us 
who do want an explicit statement like that?

-Michel