Is this meant to be possible?

[ted]

Fantastic !! (thanks !)

so is:
   createDynamicInstance(ClassInfo type) { return type.create(); }
the correct implementation ?? - it certainly seems to work...




Adam D. Ruppe wrote:

> On Tuesday, 18 February 2014 at 00:31:22 UTC, ted wrote:
>> public interface IProvider
>> {
>>     string providedType();
>>     T createInstance(T)();
> 
> This will cause the linker problem because templates cannot be
> virtual. This is declaring a final method in the interface that
> is never implemented.
> 
> The reason they can't be virtual is that an interface consists of
> an array of function pointers. Since templates might form
> multiple functions based on their compile-time arguments, the
> compiler can't know how many slots to reserve in that array for
> it.
> 
> 
> What you can do is something like this:
> 
> interface IProvider {
>     // this is a final method with an implementation right here
>     T createInstance(T)() {
>           auto i = cast(T) createDynamicInstance(typeid(T));
>           if(i is null) throw new Exception("Couldn't create " ~
> T.stringof);
>           return i;
>     }
> 
>     string providedType(); // virtual function
>     Object createDynamicInstance(ClassInfo type); // virtual
> }
> 
> 
> Then in the class, implement createDynamicInstance based on the
> classinfo instead of the template. Your other code for add and
> get should continue to work.