template condition

[Andrej Mitrovic]

On 9/27/12, Timon Gehr <timon.gehr at gmx.ch> wrote:
> snip

Perhaps he meant something like this:

struct Foo(T : Object) { }
struct Foo(T) if (is(T : Object )) { }

void main()
{
    Foo!Object x;
}

The difference is the first template is a specialization, and the
second has a constraint. The first one will match better than the
second one even though both templates can be instantiated with
'Object'.

The constraint version is more flexible but the specialization might
be shorter to write.  http://dlang.org/template.html