Is this meant to be possible?

[ted]

I've been using D (at a primitive level) for a while now at work (a large 
test-harness that exercises our main code. The harness launches and monitors 
multiple processes with multiple threads and performs actions on those 
processes to ensure correct behaviour). 

I am wanting to stretch my 'D' wings. I'm having some problems with trying 
to do the following (reduced case) - and I'm wanting to know if D will even 
(ever) allow it. Main reason is that I'm porting 'Ash' - a component/entity 
system written in actionscript, which uses this type of construct. The key 
issue is that if the line in main() is uncommented - a linker error occurs. 

Clearly, there is a 'visibility' issue of 'provider' regarding 'TestClass'. 
However, even if I add 'import main:TestClass' into module 'provider' - (and 
introduce a compile-time circularity that I absolutely do not want) - it 
still causes the link error - I guess the necessary information is lost 
through the IProvider interface.


-------------------------------------
module IProvider;

public interface IProvider
{
    string providedType();
    T createInstance(T)();
}
-------------------------------------
module provider;

import IProvider;

public class Provider(T): IProvider
{
    string providedType() { return T.classinfo.stringof;}
    public T createInstance(T)() { return new T; }
}
-------------------------------------
module manager;

import provider;
import IProvider;

public class Manager
{
    private { IProvider[ClassInfo] mProviders;  }

    public void add(T)() { mProviders[T.classinfo] = new Provider!T(); }
    
    public IProvider get(T)() {
        if ( T.classinfo in mProviders )
            return mProviders[ T.classinfo ];
        else
            return null;
    }
}
-------------------------------------
import manager;
import IProvider;
import std.stdio;

void main()
{
    auto mgr = new Manager();
    mgr.add!TestClass();
    IProvider provider = mgr.get!TestClass();
    writeln("managed type: ", provider.providedType);
    //auto tmp = provider.createInstance!TestClass(); 
		// Linker error if above line is uncommented
}

class TestClass
{
    public int value;
}
-------------------------------------