[Python-Dev] PEP 3103: A Switch/Case Statement
Fredrik Lundh
fredrik at pythonware.com
Thu Jun 29 16:38:20 CEST 2006
Eric Sumner wrote:
>> You mean something like this?:
>>
>> switch x in colours:
>> case RED:
>> # whatever
>> case GREEN:
>> # whatever
>> case BLUE:
>> # whatever
>>
>> I think Guido's right. It doesn't solve the underlying problem because the
>> compiler still has to figure out how to build a dispatch table from the
>> possible values in colours to the actual bytecode offsets of the cases.
>
> To implement this, you actually need two lookup tables: one particular
> to the switch that maps labels to bytecode offsets, and one in the
> dispatch table to map values to labels. The former is built when the
> switch is compiled, and the latter is built wherever the dispatch
> table is defined. Each lookup is still O(1), so the whole operation
> remains O(1).
what's a "label" ?
</F>
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