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

Fredrik Lundh fredrik at pythonware.com
Sun Jun 25 21:20:34 CEST 2006

Phillip J. Eby wrote:

I don't see this as much of a problem, really: we can simply restrict the optimization to well-known data types ("homogenous" switches using integers or strings should cover 99.9% of all practical cases), and then add an opcode that checks uses a separate dispatch object to check if fast dispatch is possible, and place that before an ordinary if/elif sequence. What about switches on types? Things like XML-RPC and JSON want to be able to have a fast switch on an object's type and fall back to slower tests only for non-common cases.

good point (and nice example).

for t in obtype.mro: switch t: case int: ...; break case str: ...; break else: continue else: # not a recognized type

but I wonder how confusing the "break inside switch terminates the outer loop" pattern would be to a C programmer...

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