[Python-Dev] Switch statement (original) (raw)

Jim Jewett jimjjewett at gmail.com
Mon Jun 26 22:30:03 CEST 2006

In http://mail.python.org/pipermail/python-dev/2006-June/066475.html Nick Coghlan wrote:

(Unlike Jim, I have no problems with restricting switch statements to hashable objects and building the entire jump table at once - if what you want is an arbitrary if-elif chain, then write one!)

I haven't been clear. I don't object to building the entire table at once. I object to promising that this will happen, which forbids other implementations from using certain optimizations.

I would prefer something like:

There is no guarantee on how often or when the case statements will be evaluated, except that it will be after the enclosing scope exists and before the relevant test is needed. If a case expression has side effects, the behavior with respect to these side effects is explicitly undefined.

-jJ

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