Template design with required type parameters?

[Benji Smith]

news:ej31kf$1po9$1 at digitaldaemon.com...
> Is it possible to design a template that requires, at compile time, that 
> it's parameters be of a particular type?

JC wrote:
> void goDancing(T)(T o) {
> in {
>   static if (!is(T : ICanDance)) // check if T is derived from ICanDance
>     static assert(false, "Type must be of type 'ICanDance'.");
> }
> body {
>   o.dance();
> }

He was probably thinking something along the lines of the C# construct:

   class SortedMap<K, V> where K : IComparable {
     // ...
   }

It looks like the contract & assertion will accomplish the same thing, 
though not quite as cleanly as the parametric constraint in C#.

--benji