Andrei's interface requests

[Jason House]

2786 also mentions struct using interfaces... I take it Andrei has come around on that.

I think I'd prefer for polymorphic and static/struct interfaces to be distinct from each other.

I also agree that 2785 introduces a dangerous construct when mixed with normal interfaces. 


Christopher Wright Wrote:

> Andrei has put up a few enhancement requests in the bugzilla:
> http://d.puremagic.com/issues/show_bug.cgi?id=2784
> http://d.puremagic.com/issues/show_bug.cgi?id=2785
> http://d.puremagic.com/issues/show_bug.cgi?id=2786
> 
> These are intended to change interfaces from being solely a tool of 
> polymorphism into a way of specifying type constraints. The additions 
> recommended can only be used at compile time (constructors, static 
> functions, and nested types).
> 
> I grant that it would be quicker and clearer to write:
> interface Foo
> {
>     static void stuff();
>     this (int);
> }
> template Template(Arg : Foo) {}
> 
> than to write:
> template Template(Arg) if (is (typeof (new Arg(0)) && 
> isStaticFunction!(Arg, "stuff")) {}
> 
> However, I'm not sure whether this would be used much at all, and it 
> deserves some discussion.
> 
> One detail of #2785 seems problematic:
> interface Foo
> {
>      extern void bar(int, Foo, double);
> }
> 
> meaning that a non-member function bar should exist that accepts an int, 
> *the implementor of Foo*, and a double.
> 
> This is a huge and silent divergence from the standard meaning of using 
> the interface name; it would allow:
> class C : Foo
> {
> 	static void bar(int, C, double);
> }
> 
> and disallow:
> class C : Foo
> {
> 	static void bar(int, Foo, double);
> }
> 
> Thoughts? Any concerns that I have not raised? I don't do sufficient 
> metaprogramming to find any of this useful, I admit.