case/switch statement?

[D H]

Peter Hansen wrote:
> D H wrote:
> 
>> Peter Hansen wrote:
>>
>>> With a case statement, on the other hand, you *know* that it must be 
>>> just simple conditionals (a series of x == some_constant tests), so 
>>> you don't need to look at all the cases, just the one that interests 
>>> you.
>>
>>
>> Since you and Steve Holden agree that a case statement is useful, why 
>> don't you propose it for python, or add it to the wiki page for Python 
>> 3000.
> 
> 
> Two simple reasons.
> 
> 1. You forgot my previous comment that "in current Python the equivalent 
> approach is, of course, a dictionary of some kind, though it's arguable 
> whether this is as clean in many cases as a case statement would be."

I didn't forget that.  I never read it, and I don't see the relevance to 
my suggestion.  Now that I've read it, I would hardly call using a 
dictionary as a switch statement, the "equivalent".  The fact that 
people use a dictionary as a conditional is a python wart.

> 2. Just because something is "useful" doesn't mean it should be added to 
> Python.  The bar should be set much higher, and should include at least 
> "and significantly better than any existing alternative way of doing the 
> same thing."  Now go read point 1 again... ;-)

Now go read my message again.  I made a suggestion to you.  I didn't say 
that a switch statement should be added myself.  I would never propose 
that because the chances of it being added are microscopic.


> My point was not to suggest that I want a case statement in Python, nor 

Neither was the MY point, which you seem to have inferred.

> even that a case statement is a good thing to have in a language (though 
> it might be... it's not my place to say).  My point was simply to point 
> out that performance is not the only reason to use a case statement.

I don't think you could have misread my simple suggestion to you any 
more completely than you did.