Finding class template instantiations via runtime reflection (for openmethods)

[b4s1L3]

On Thursday, 21 September 2017 at 20:32:38 UTC, Jean-Louis Leroy 
wrote:
> It did not take long! Someone tried to create templatized open 
> methods and it didn't work right of the box. I expected that, 
> but in fact there may be a bit of hope. You cannot have virtual 
> function templates in C++ or in D because the layout of the 
> vtables have to be known at compile time - but openmethods 
> creates its method tables at runtime so maybe it can be made to 
> work.
>
> I stumbled upon a problem very quickly: it seems that classes 
> that come from class template instantiations are not registered 
> in ModuleInfo - see below,
>
> [...]
>
> Neither 'Bar!int' nor 'BarInt' appear in 'localClasses'.
>
> Ideas?

Yeah. You can setup a custom registry that maps names to their 
TypeInfo_Class.
I do something similar in iz (though the real point in iz is a 
GC-free factory but the principle of the registry would be the 
the same for you)

Example:

---
/+ dub.sdl:
    name "dub_script"
    dependency "iz" version="0.6.0"
+/
module dub_script;

import iz.memory, std.stdio;

class Foo(T){this(){writeln("fooDeInt");}}
TypeInfo_Class[string] registry; // you need that...

static this()
{
     registerFactoryClass!(Foo!int)(registry); // ...and that, 
maybe  with another name
}

void main()
{
     auto fooDeInt = iz.memory.factory(registry, "Foo!int");
     destruct(cast(Object) fooDeInt);
}
---