Question about explicit template instantiation

[Janice Caron]

On 10/02/2008, Edward Diener <eddielee_no_spam_here at tropicsoft.com> wrote:
> I still do not understand what the object used for the instantiation is.
> In your example above what is:
>
> A!(int)
>
> ? Is it some kind of namespace ?

Yes. It is exactly a namespace.



> Can I say:
>
> A!(int) x;
>
> ?

Sometimes, but only in special case. If you don't specify a member of
the namespace, then the compiler will /assume/ a member whose name is
the same as that of the template. So, if we have:

    template A(T)
    {
        int A;
    }

then

    A!(int) x;

would be shorthand for

    A!(int).A x;

But if there wasn't an A in the namespace, then it wouldn't compile.
That little "trick" is really, really useful, because it can make for
a lot less typing. So - in general - A!(T) with no member, is the same
thing as A!(T).A, if A!(T).A exists.

/What/ is it, depends. It's whatever A!(T).A is.