How about a Hash template?

[Jacob Carlborg]

On 2011-04-28 21:46, Timon Gehr wrote:
> Andrei Alexandrescu wrote:
>> On 4/28/11 11:00 AM, Alexander wrote:
>>> On 28.04.2011 17:46, Andrej Mitrovic wrote:
>>>
>>>> It works, but it makes the if statement ugly again. :)
>>>
>>>     Well, just a bit - still much better than (var == "..." || var = "...">||
> var == "..." ...), don't you think so? ;)
>>>
>>>     If compiler would support special "in" usage, automatically expanding
>>> values on the right to series of comparisons (like "var in [1,2,3,4,5]"),>>it
> would be really nice, of course :)
>>
>> That was discussed, too. Walter and I support that although it's a
>> special case. We didn't get around to talk the purist police into
>> accepting it.
>>
>> Andrei
>
> Why is this a special case? The 'in' could be extended operator to generally work
> on arrays (using a simple linear search). The compiler could then optimize the
> given expression the way suggested (actually even to 1<=var&&var<=5).
>
> Why is 'in' not currently defined on arrays? To me it seems like a left-out that
> should be fixed, because it has quite obvious and useful semantics.
>
> Timon

This has been discussed many times before and the general argument 
against it is that "in" is available for associative arrays and it tests 
for keys. With arrays it would test for values.

-- 
/Jacob Carlborg