How to pass a pointer of type const in the EMSCRIPTEN_WRAPPER about emscripten

[brendandahl]

As for why const std::shared_ptr works, that will be a const reference which has a helper static WireType toWireType(const T& v) { for sending it to JS so it works.

[brendandahl]

Embind generally doesn't like raw pointers being sent across since it unclear who owns the object. Can you instead use a std::shared_ptr?

[JankingWonn]

Embind generally doesn't like raw pointers being sent across since it unclear who owns the object. Can you instead use a std::shared_ptr?

Thank you @brendandahl. I'm also bothered by this issue. When I tried to change the function to void passConstObj(const std::shared_ptr<PolyDerived> o), the problem was solved.

But I have a question, ignoring the question of whether embind likes the original pointer preference (because it doesn't affect the compilation of PolyDerived* type arguments), why const PolyDerived* can't compile the same const argument, but const std::shared_ptr<PolyDerived> can

[brendandahl]

I misremembered, I thought val::call had the same restrictions as bind.h function bindings where you must explicitly pass allow_raw_pointers if you want to use pointers as arguments. val::call doesn't appear to have that restriction, so yes it is strange that const pointers don't work. I'm not the original author of this code so I'm not sure what the intent was there or if it was just an oversight.

It seems reasonable to automatically remove the const in the val.h code.

[brendandahl]

There was a relevant discussion previously #7292 but nothing ever came of it.

[JankingWonn]

Thanks @brendandahl again. Although I didn't figure it out thoroughly, at least there was a solution.