On 5/11/05, Nick Coghlan <ncoghlan at gmail.com> wrote:
> The gist is that the alternative is to require an __exit__() method to raise
> TerminateBlock in order to suppress an exception.
So I didn't see any examples that really needed TerminateBlock to
suppress an exception. If the semantics of a do-statement was simply:
stmt = EXPR1
try:
stmt_enter = stmt.__enter__
stmt_exit = stmt.__exit__
except AttributeError:
raise TypeError("User defined statement template required")
VAR1 = stmt_enter() # Omit 'VAR1 =' if no 'as' clause
exc = ()
try:
try:
BLOCK1
except:
exc = sys.exc_info()
finally:
stmt_exit(*exc)
would this make any of the examples impossible to write? All you have
to do to suppress an exception is to not reraise it in __exit__.
These semantics would make a normally completed BLOCK1 look like a
BLOCK1 exited through return, break or continue, but do we have any
use cases that actually need this distinction? I couldn't see any,
but I've been reading *way* too many PEP 310/340 posts so probably my
eyes are just tired. ;-)
If you want the default to be that the exception gets re-raised
(instead of being suppressed as it is above), I think you could just
change the finally block to something like:
finally:
if stmt_exit(*exc):
raise exc[0], exc[1], exc[2]
That would mean that if any nonzero object was returned from __exit__,
the exception would be reraised.
But, like I say, I've been reading this thread way too much, so I'm
probably just missing the TerminateBlock use cases. =)
STeVe
--
You can wordify anything if you just verb it.
--- Bucky Katt, Get Fuzzy
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