• Nicholas Wilson (32/32) Oct 27 2020 Given
• Adam D. Ruppe (13/24) Oct 28 2020 So I'm not sure you can do what you want to do - D doesn't have
• Jacob Carlborg (6/22) Oct 29 2020 Are you looking for `TemplateArgsOf` [1] ?

Nicholas Wilson <iamthewilsonator hotmail.com> writes:

Given

template ScopeClass(C)
{
     //...
}


where C is a, possibly templated, class I want the eponymous 
member of ScopeClass!(C) to have the same templatedness (both 
parameters and arguments)as C.
For a non-template C this is a simple as:

template ScopeClass(C)
{
     class ScopeClass
     {
          // implement members with compile time reflection
     }
}

but for a templated C this is tricker as I can't use a template 
sequence parameter (...) unless C uses it in the same position 
(I'm trying to generate a mangle from it so it needs to be 
exact). Given

class A(T,int,args...) {}
alias C = A!(int, 0, float);

I need `ScopeClass!C` to be

template ScopeClass(C)
{
     class Anon(T,int,args...) // name doesn't matter
     {
          // implement members with compile time reflection
     }

     alias ScopeClass = Anon!(int, 0, float);
}

How do I do this?

Adam D. Ruppe <destructionator gmail.com> writes:

On Wednesday, 28 October 2020 at 05:51:14 UTC, Nicholas Wilson 
wrote:
 class A(T,int,args...) {}
 alias C = A!(int, 0, float);

 I need `ScopeClass!C` to be

 template ScopeClass(C)
 {
     class Anon(T,int,args...) // name doesn't matter
     {
          // implement members with compile time reflection
     }

     alias ScopeClass = Anon!(int, 0, float);
 }

So I'm not sure you can do what you want to do - D doesn't have 
any way to reflect on template parameters (though you CAN extract 
arguments I don't think it really helps here since you can't tell 
if the arguments were from `int, float` or from `T...` for 
example).

But like I don't really get why you need this. Can't you just use 
the arguments C already has and not have the extra layer? So 
you'd treat templated C the same was as non-templated C, and then 
if you want the mangle, just use like C.mangleof instead of 
trying to reconstruct it.

What's the bigger picture here?

Jacob Carlborg <doob me.com> writes:

On Wednesday, 28 October 2020 at 05:51:14 UTC, Nicholas Wilson 
wrote:

 but for a templated C this is tricker as I can't use a template 
 sequence parameter (...) unless C uses it in the same position 
 (I'm trying to generate a mangle from it so it needs to be 
 exact). Given

 class A(T,int,args...) {}
 alias C = A!(int, 0, float);

 I need `ScopeClass!C` to be

 template ScopeClass(C)
 {
     class Anon(T,int,args...) // name doesn't matter
     {
          // implement members with compile time reflection
     }

     alias ScopeClass = Anon!(int, 0, float);
 }

 How do I do this?

Are you looking for `TemplateArgsOf` [1] ?

[1] https://dlang.org/phobos/std_traits.html#TemplateArgsOf

--
/Jacob Carlborg