Bug in D!!!

[Biotronic via Digitalmars-d-learn]

On Thursday, 31 August 2017 at 15:48:12 UTC, EntangledQuanta 
wrote:
> On Thursday, 31 August 2017 at 10:34:14 UTC, Kagamin wrote:
>> On Thursday, 31 August 2017 at 00:49:22 UTC, EntangledQuanta 
>> wrote:
>>> I've already implemented a half ass library solution.
>>
>> It can be improved alot.
>
> Then, by all means, genius!

Enjoy!

mixin template virtualTemplates(alias parent, alias fn, T...) {
     import std.meta;
     alias name = Alias!(__traits(identifier, fn)[1..$]);
     mixin virtualTemplates!(parent, name, fn, T);
}

mixin template virtualTemplates(alias parent, string name, alias 
fn, T...) {
     import std.traits;
     static if (is(parent == interface)) {
         template templateOverloads(string name : name) {
             alias templateOverloads = T;
         }
         alias Types = T;
     } else {
         alias Types = templateOverloads!name;
     }

     mixin(virtualTemplatesImpl(name, Types.length, is(parent == 
class)));
}

string virtualTemplatesImpl(string name, int n, bool implement) {
     import std.format;
     string result;
     foreach (i; 0..n) {
         auto body = implement ? format(" { return 
fn!(Types[%s])(args); }", i) : ";";
         result ~= format("ReturnType!(fn!(Types[%s])) 
%s(Parameters!(fn!(Types[%s])) args)%s\n", i, name, i, body);
     }
     return result;
}

interface I {
     void _Go(T)(T s);
     void _Leave(T)(T s);
     mixin virtualTemplates!(I, _Go, int, short, float, double);
     mixin virtualTemplates!(I, "Abscond", _Leave, int, short, 
float, double);
}

class C : I {
     void _Go(T)(T s) { }
     void _Leave(T)(T s) { }
     mixin virtualTemplates!(C, _Go);
     mixin virtualTemplates!(C, "Abscond", _Leave);
}

unittest {
     I c = new C();

     c.Go(3.2);
     c.Abscond(3.4f);
}

Does not support multiple template parameters, or template value 
parameters. Use at own risk for any and all purposes.