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[Python-Dev] Simple Switch statement

Phillip J. Eby pje at telecommunity.com
Sun Jun 25 03:45:14 CEST 2006 
At 05:30 PM 6/24/2006 -0700, Raymond Hettinger wrote:
>[Phillip Eby]
> > I would like to be able to use switches on types, enumerations, and the 
> like.
>
>Be careful about wanting everything and getting nothing.
>My proposal is the simplest thing that gets the job done for key use cases 
>found
>in real code.

It's ignoring at least symbolic constants and types -- which are certainly 
"key use cases found in real code".

Besides which, this is Python.  We don't select a bunch of built-in types 
and say "these are the only types that work".  Instead, we have protocols 
(like __hash__ and __eq__) that any object may implement.

If you don't want expressions to be implicitly lifted to function 
definition time, you'd probably be better off arguing to require the use of 
explicit 'static' for non-literal case expressions.

(Your reverse mapping, by the way, is a non-starter -- it makes the code 
considerably more verbose and less obvious than a switch statement, even if 
every 'case' has to be decorated with 'static'.)
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