Using embind to generate TypeScript typings

[boyanio]

Hello. To export C++ structs and classes, one can use embind. As the export is very explicit, I was thinking, one could use embind to generate TypeScript typings (.d.ts) too. I would be happy to hear your comments on that :-)

[isc30]

Yes, I like that idea. I would go even further and introduce some kind of "ownership" expressed by marker interfaces. Something like this:

interface owns<T> extends T
{
    delete(): void;
}

This way your API can be explicit on what objects you need to call .delete() (this is very similar to IDisposable interface in C# but in a mixin version).

[boyanio]

Good point! If we look at the class example in the documentation, we could generate the following typings:

declare namespace Module {
    export interface Deletable {
        delete();
    }

    export interface MyClass extends Deletable {
        x: number;
        incrementX(): void;
    }

    export var MyClass: {
        new(x: number, y: string): MyClass;

        getStringFromInstance(a: MyClass): string;
    }
}

As not everyone uses TypeScript, this part should be optional. Could be a separate bind switch, for example

emcc --bind --ts-typings -o quick_example.js quick_example.cpp

[isc30]

I think the interface inheritance should go the other way around. You should be able to mark some type as Owning when the delete() function is available. This can be easily achieved with mixin interfaces.

declare namespace Module
{
    export interface Owner<T> : T
    {
        delete();
    }

    export interface MyClass
    {
        x: number;
        incrementX(): void;
    }

    export var MyClass:
    {
        new(x: number, y: string): Owner<MyClass>; // js needs to destroy it
        getSomeNotOwningPointer(): MyClass; // js doesnt need to destroy it

        getStringFromInstance(a: MyClass): string;
    }
}

With this design, Owner<T> is assignable to T so it can be used in non-owning contexts.

[endel]

I believe this is totally possible, given the verbosity and details we provide to EMSCRIPTEN_BINDINGS. Has anyone started implementing this? I'd love to contribute!

[isc30]

as far as I know no one started working on this

[wffurr]

I'm working with a prototype of this, created by a colleague. If I can get it working on a couple of different embind examples, then I will see about contributing it upstream.

[mathiasi]

Any updates on this?

[wffurr]

The tool itself works fine for the subset of embind it supports. I'm having trouble making it work for my project due to project-specific issues. I'm also not sure the best way to integrate it with the Emscripten toolchain. I might have something by the end of the year.

[stale]

This issue has been automatically marked as stale because there has been no activity in the past year. It will be closed automatically if no further activity occurs in the next 30 days. Feel free to re-open at any time if this issue is still relevant.