Unusual template specialisation behavior

[Matthias Walter]

Christopher Wright Wrote:

> Matthias Walter wrote:
> > Hello guys,
> > 
> > Here's a (minimal) code snippet for my problem:
> > 
> > | struct Expression (R, E) { }
> > | 
> > | struct ResolveReference (T)
> > | {
> > |     alias T reference_type;
> > | }
> > | 
> > | struct ResolveReference (T : Expression !(R, E))
> 
> The compiler should have caught this, I think. You have R and E, but 
> they aren't defined. They default to int (which is why you saw that 
> behavior), but not being defined, they should be a compile-time error.
> 
> The proper way to do this, unfortunately, involves static if rather than 
> overloading. At least if you want your users to supply a single argument 
> in all cases.

Thanks for that hint. How would such a static if look like?

I currently have 

| static if (is (T == struct)).

This works for distinguishing native datatypes like int from my Expression-Templates.
But is there a native way to statically check, whether T is some specialisation like
 "T == Expression !(R, E)" (for all R, E).

best regards
Matthias Walter