Eponymous template with full template syntax

[Ali Çehreli]

On 07/01/2013 02:10 PM, monarch_dodra wrote:

 >> That is confusing.
 >
 > UFCS construction: Yes.

I *think* I did not know it but I can't be sure. :)

struct S
{
     int i;
}

void main()
{
     static assert (S(42) == 42.S);
}

It works with 2.063 (v2.064-devel-a1a1537 too).

 > The rest, not so much:
 >
 > The idea is that once a template is "eponymous", it *fully* becomes the
 > eponymous function/type/value (s). Every other function, regardless of
 > public/private*, simply seizes to exist to the outside world. You can't
 > make a "qualified" call to an eponymous template, because the
 > "qualification" is already the call.

A single definition with the same name makes it an eponymous template. I 
used to think that the template should also have a single definition.

So, currently other definitions act as implementation details of the 
template. The following template sees the local S, not the module-level one:

struct S
{
     int[10] i;
}

template epo(T)
{
     size_t epo()
     {
         return S.sizeof;  // <-- epo.S, not .S
     }

     struct S
     {
         int i;
     }

     double foo()
     {
         return 1.5;
     }
}

void main()
{
     assert(epo!int() == int.sizeof);  // <-- yes, epo.S

     mixin epo!int;
     assert(foo() == 1.5);
}

Also note that mixing in the template is still possible but it is an 
orthogonal feature anyway.

Ali