[Guido] > >The 'oke' argument is so that the author of transactional() can decide > >what to do with a non-local goto: commit, rollback or hit the author > >over the head with a big stick.
[Phillip J. Eby] > Since this is just a replacement for a try/except/finally block, I'd expect > that in a transactional case that a non-local goto would work the same as > any other non-exception exit. > > ISTM that the resource block use cases are: > > * Save the current state of something, modify it, and then restore the old > state once the block completes (try/finally, used for locking, redirection, > signals, decimal context, etc.) > > * Automatically roll back partially-done work in case of exception, and/or > "roll forward" completed work (try/except/else, used for "transaction" > scenarios) > > * Release allocated resource(s) after use (try/finally, used to close files > and suchlike) > > None of these, AFAICT, benefit from differing behavior in the presence of > nonlinear (but non-exceptional) control flow. It just seems too magical to > me in the new context. When we were talking about a "block" construct or > user-defined syntax, it made more sense because you could actually redefine > the *meaning* of those constructs to some extent -- and because the > *target* of the break and continue statements at least was the block > itself, not some containing block. That works for me; I was just hypothesizing about the needs of others, but personally I'm fine with not knowing. I guess part of my motivation is also that this information is readily available intenally when a finally-clause is executed, since when the clause completes a pending non-local goto has to be resumed. But there's no reason to expose *all* internal state information... So the signature of __exit__ is just what sys.exc_info() returns. -- --Guido van Rossum (home page: http://www.python.org/~guido/) _______________________________________________ Python-Dev mailing list Python-Dev@python.org http://mail.python.org/mailman/listinfo/python-dev Unsubscribe: http://mail.python.org/mailman/options/python-dev/archive%40mail-archive.com
