template ref parameter

[Jack Applegame]

> alias void function(ref int) funcType;
>
> void foo(ref int a) { a--; }
>
> struct functor(A...) {
>   A[0] func;
> }
> void main()
> {
>   functor!funcType f;
>   f.func = &foo;
> }

I think the best way is using @property.

alias void function(ref int) funcType;
void foo(ref int a) { a--; }

struct functor(A...) {
   @property void func(A fp) { m_func = fp; }
   A m_func;
}
void main()
{
   functor!funcType f;
   f.func = &foo;
}