case/switch statement?

[Philippe C. Martin]

Any speed issue ?


invalidemail at aerojockey.com wrote:

> Philippe C. Martin wrote:
>> Leif K-Brooks wrote:
>>
>> > Joe Stevenson wrote:
>> >> I skimmed through the docs for Python, and I did not find anything
>> >> like
>> >> a case or switch statement.  I assume there is one and that I just
>> >> missed it.  Can someone please point me to the appropriate document,
>> >> or
>> >> post an example?  I don't relish the idea especially long if-else
>> >> statements.
>> >
>> > If you really want one, you could use
>> > <http://aspn.activestate.com/ASPN/Cookbook/Python/Recipe/410692>.
>>
>> I _love_ Python!
> 
> 
> Well, if you loved that, here's something even more evil.  This was
> Bengt Richter's original idea that Cliff Wells and I improved upon.
> First define some functions and classes:
> 
> . _cache = {}
> .
> . class _BaseCaseException(Exception):
> .     pass
> .
> . def switch(v):
> .     if v not in _cache:
> .         class _CaseException(_BaseCaseException):
> .             pass
> .         _cache[v] = _CaseException
> .     raise _cache[v]
> .
> . def case(v):
> .     if v not in _cache:
> .         class _CaseException(_BaseCaseException):
> .             pass
> .         _cache[v] = _CaseException
> .     return _cache[v]
> .
> . default = _BaseCaseException
> 
> 
> Then you can define a switch statement like this:
> 
> . x = 2
> .
> . try: switch(x)
> .
> . except case(1):
> .     print "Case 1"
> .
> . except case(2):
> .     print "Case 2"
> .
> . except case(3):
> .     print "Case 3"
> .
> . except default:
> .     print "Default"
> .
> . except NameError:
> .     print "You can still catch regular exceptions like NameError"
> 
> 
> 
> I-love-Python-too-but-this-isn't-why-ly yr's,
>