Finding out if T is a specialization of another template

[Lars T. Kyllingstad]

On Fri, 18 Feb 2011 20:37:38 +0000, Sean Eskapp wrote:

> == Quote from Lars T. Kyllingstad (public at kyllingen.NOSPAMnet)'s article
>> On Fri, 18 Feb 2011 17:16:02 +0000, Sean Eskapp wrote:
>> > I was given this code, to check if Y is a specialization of Bar. How
>> > does it work?
>> >
>> > class Bar(T)
>> > {
>> > }
>> >
>> > void foo(Y)()
>> > {
>> >     static if (is(Y Z == Bar!Z))
>> >     {
>> >         // Here, Z is now an alias to whichever type Bar is //
>> >         instantiated with.
>> >     }
>> >     else
>> >     {
>> >         // Z is invalid here.
>> >     }
>> > }
>> I'm not sure what you mean by "how does it work".  If it's the is()
>> expression you're wondering about, it's documented here:
>> http://www.digitalmars.com/d/2.0/expression.html#IsExpression -Lars
> 
> Ah, yes. I'd checked the is documentation, but whenever I tried using
> that is expression outside of an if statement, it complained about my
> usage, so I assumed it had something to do with if statements.

Yeah, is() has a few extra features when it's combined with 'static 
if'. :)

-Lars