[Python-Dev] PEP 343 updated

[Nick Coghlan]

Guido van Rossum wrote:
> On 10/16/05, Nick Coghlan <ncoghlan at iinet.net.au> wrote:
> I hope you reverted the status to "Proposed"...

I hadn't, but I've now fixed that in CVS (both in the PEP and the PEP index), 
and added some text into the PEP saying why it was reverted to Draft.

> On the latter: I think it shouldn't; I don't like this kind of magic.
> I'll have to read it before I can comment on the rest.

I don't particularly like treating __with__ specially either, but I'm not sure 
I like the alternative.

The alternative is that we'd never be able to safely define a __with__ method 
directly on generators - the reason is that we would want a "def __with__" 
where the @context decorator has been forgotten to trigger a TypeError when it 
is used. If generator-iterators were to provide a context manager to 
automatically invoke close(), then leaving out "@context" would result in a 
very obscure bug (as g.close() would be used to finish the context, instead of 
g.next() or g.throw()).

On the other hand, if the context decorator is invoked automatically when a 
generator function is supplied to populate the __with__ slot, then using a 
generator to define a __with__ method will "just work", instead of "only works 
if you also apply the context decorator"

Cheers,
Nick.

-- 
Nick Coghlan   |   ncoghlan at gmail.com   |   Brisbane, Australia
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