Get struct template types

[Jakob Ovrum]

On Tuesday, 4 February 2014 at 09:30:22 UTC, ed wrote:
> Hi,
>
> given a struct like so:
>
> struct S(alias N, T) {...}
>
> is there a way to get the template parameters of S? Something 
> like:
>
> S.typetuple[0] == N,
> S.typetuple[1] == T
>
> I've had a look at std.typecons and std.typetuple but I don't 
> see what I'm missing something and cannot see a way to do the 
> above.
>
> Thanks,
> ed

Use type deduction:

---
struct S(size_t n, T) {}

enum isS(T) = is(T == S!(n, U), size_t n, U);

template isS(T, size_t n)
{
     static if(is(T == S!(n2, U), size_t n2, U))
         enum isS = n == n2;
     else
         enum isS = false;
}

alias MyS = S!(3, float);

static assert(isS!MyS);
static assert(isS!(MyS, 3));
static assert(is(MyS == S!(3, float)));
---