On 10/4/05, Jason Orendorff <[EMAIL PROTECTED]> wrote:
> This:
>
> with EXPR as VAR:
> BLOCK
>
> expands to this under PEP 342:
>
> _cm = contextmanager(EXPR)
> VAR = _cm.next()
> try:
> BLOCK
> except:
> try:
> _cm.throw(*sys.exc_info())
> except:
> pass
> raise
> finally:
> try:
> _cm.next()
> except StopIteration:
> pass
> except:
> raise
> else:
> raise RuntimeError
Where in the world do you get this idea? The translation is as
follows, according to PEP 343:
abc = EXPR
exc = (None, None, None)
VAR = abc.__enter__()
try:
try:
BLOCK
except:
exc = sys.exc_info()
raise
finally:
abc.__exit__(*exc)
PEP 342 doesn't touch on the expansion of with-statements at all.
I think I know where you're coming from, but please do us a favor and
don't misrepresent the PEPs. If anything, your proposal is more
complicated; it requires four new APIs instead of two, and requires an
extra call to set up (__with__() followed by start()).
Proposals like yours (and every other permutation) were brought up
during the initial discussion. We picked one. Don't create more churn
by arguing for a different variant. Spend your efforts on implementing
it so you can actually use it and see how bad it is (I predict it
won't be bad at all).
--
--Guido van Rossum (home page: http://www.python.org/~guido/)
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