Hi everyone,

My project includes lots of .Net interop via C linkage. One of the things I need to do is refer in C# to an interface declared in the D code, and then to actually work with the interface concretely in the D layer. So, I need to get a TypeInfo_Interface object from a string passed in from C#.

The problem isn't in marshaling the string between C# and D, but rather what to do with the string once I have it in D.

So in the D code, where interfaceName is the fully qualified name of an interface, e.g.  "MyPackage.MyModule.MyInterface", what I would like is something like:


TypeInfo_Interface theInterface = new TypeInfo_Interface(interfaceName);


But there's no such constructor.

Apologies if this seems like it should be obvious, but I couldn't find anything in the forums or the wider web. :)

thanks,
Thalamus

On Wednesday, 22 June 2016 at 15:15:51 UTC, Thalamus wrote:
> Hi everyone,
>
> My project includes lots of .Net interop via C linkage. One of the things I need to do is refer in C# to an interface declared in the D code, and then to actually work with the interface concretely in the D layer. So, I need to get a TypeInfo_Interface object from a string passed in from C#.
>
> The problem isn't in marshaling the string between C# and D, but rather what to do with the string once I have it in D.
>
> So in the D code, where interfaceName is the fully qualified name of an interface, e.g.  "MyPackage.MyModule.MyInterface", what I would like is something like:
>
>
> TypeInfo_Interface theInterface = new TypeInfo_Interface(interfaceName);
>
>
> But there's no such constructor.

No need for a constructor. typeid() returns a static instance that's pre-allocated.

> Apologies if this seems like it should be obvious, but I couldn't find anything in the forums or the wider web. :)

No problem. What you need to do is to create a registry with all the possible TypeInfo_Interfaces. This registry will have the form of an associative array. Each TypeInfo_Interface will be selectable with the fully qualified string, for example:

    __gshared TypeInfo_Interface[string] registry;

    interface Foo{}
    interface Bar{}

    static this()
    {
        registry[typeid(Foo).toString] = typeid(Foo);
        registry[typeid(Bar).toString] = typeid(Bar);
    }

That's the basic idea but with introspection (foreach(member; traits....) you should be able to automate the creation of the registry, in a smarter way.

On Wednesday, 22 June 2016 at 15:43:08 UTC, Basile B. wrote:
> On Wednesday, 22 June 2016 at 15:15:51 UTC, Thalamus wrote:
>> [...]
>
> No need for a constructor. typeid() returns a static instance that's pre-allocated.
>
> [...]

Thanks Basile.

On Wednesday, 22 June 2016 at 15:46:15 UTC, Thalamus wrote:
> On Wednesday, 22 June 2016 at 15:43:08 UTC, Basile B. wrote:
>> On Wednesday, 22 June 2016 at 15:15:51 UTC, Thalamus wrote:
>>> [...]
>>
>> No need for a constructor. typeid() returns a static instance that's pre-allocated.
>>
>> [...]
>
> Thanks Basile.

Hit Send too soon...

Thanks Basile. As it turned out I was already doing something very similar for mapping types to interfaces and to other types, using shared static constructors to perform registration into associative arrays, e.g.

TypeInfo_Class[TypeInfo_Class]
     and
TypeInfo_Interface[TypeInfo_Class]

So I can easily add

TypeInfo_Interface[string]
     and
TypeInfo_Class[string]

as part of the existing registration process and then expose a simple lookup method. Thanks for the good idea! :)