[Guido] > > Now it would make more sense to change the syntax to > > > > with EXPR as VAR: > > BLOCK > > > > and we have Phillip Eby's proposal.
[Greg] > Change the 'with' to 'do' and I'd be +1 on this. Great! But the devil is in the details. I want to reduce the complexity, and I'm willing to reduce the functionality somewhat. It would help if you could support this. In particular, while I like the use case transactional() (example 3 in PEP 340) enough to want some indicator of success or failure, I don't see the point of having separate __except__, __else__ and __finally__ entry points. It's unclear how these would be mapped to the generator API, and whether more than one could be called e.g. what if __else__ raises an exception itself -- will __finally__ be called? I'm sure that could be specified rigorously, but I'm not so sure that it is going to be useful and clear. I see several possible levels of information that could be passed to the __exit__ call: (1) None. This is insufficient for the transactional() use case. (2) Only a bool indicating success or failure. This is sufficient for the transactional() use case. (3) Full exception information, with the understanding that when __exit__() returns normally, exception processing will resume as usual (i.e. __exit__() is called from a finally clause). Exceptions raised from __exit__() are considered errors/bugs in __exit__() and should be avoided by robust __exit__() methods. (4) Like (3), but also distinguish between non-local gotos (break/continue/return), exceptions, and normal completion of BLOCK. (I'm not sure that this is really different from (3).) What do you think? -- --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
