feat(embind): add support for type-based overloading

[bugra9]

 class A {};
 class B : public A {};
 class C {};

 class HasOverloadedMethods {
 public:
     HasOverloadedMethods(std::string i); // javascript type of parameter: string
     HasOverloadedMethods(int i); // javascript type of parameter: number

     void foo();
     void foo(std::string i); // javascript type of parameter: string
     void foo(short i); // javascript type of parameter: number
     void foo(A i); // javascript type of parameter: A
     void foo(std::shared_ptr<C> i); // javascript type of parameter: C
     void foo(int i, int j); // javascript types of parameters: number, number
     void foo(double i); // javascript type of parameter: number
     void foo(float f) const; // javascript type of parameter: number
     void foo(B i); // javascript type of parameter: B (derived from A)
     
     static void staticFoo(std::string i); // javascript type of parameter: string
     static void staticFoo(int i); // javascript type of parameter: number
};

 // Binding code
 EMSCRIPTEN_BINDING(overloads) {
     class_<HasOverloadedMethods>("HasOverloadedMethods")
         .constructor<std::string>()
         .constructor<int>()
         // .smart_ptr_constructor("HasOverloadedMethods", &std::make_shared<HasOverloadedMethods, std::string>)
         // .smart_ptr_constructor("HasOverloadedMethods", &std::make_shared<HasOverloadedMethods, int>)
         .function("foo", select_overload<void()>(&HasOverloadedMethods::foo))
         .function("foo", select_overload<void(std::string)>(&HasOverloadedMethods::foo))
         .function("foo", select_overload<void(short)>(&HasOverloadedMethods::foo))
         .function("foo", select_overload<void(A)>(&HasOverloadedMethods::foo))
         .function("foo", select_overload<void(std::shared_ptr<C>)>(&HasOverloadedMethods::foo))
         .function("foo", select_overload<void(int, int)>(&HasOverloadedMethods::foo))
         .function("foo_double", select_overload<void(double)>(&HasOverloadedMethods::foo))
         .function("foo_float", select_overload<void(float)const>(&HasOverloadedMethods::foo))
         .function("foo_B", select_overload<void(B)>(&HasOverloadedMethods::foo))
         .class_function("staticFoo", select_overload<void(std::string)>(&HasOverloadedMethods::staticFoo))
         .class_function("staticFoo", select_overload<void(int)>(&HasOverloadedMethods::staticFoo))
         ;
 }

• Functions can be overloaded using parameter js types.
• Class methods can be overloaded using parameter js types.
• Static class methods can be overloaded using parameter js types.
• Class constructors can be overloaded using parameter js types. (constructor and smart_ptr_constructor)
• Add tests.
• Update the documentation.
• Run test/runner other.test_embind.
• Run EMTEST_SKIP_V8=1 test/runner core0 skip:core0.test_time.

[brendandahl]

For current consumers of the overload feature this is going to make things much slower, since there's a lot more work that will happen on every call to an overloaded function. Some thoughts on how we could improve this:

• First do a check for argument length, if there's only one method that matches call it. Otherwise, do the expensive type checking.
• There's a lot of split/joining and string matching. I think not relying on strings and keeping things split will be more efficient (see some comments inline).

Last, please update the documentation.

[bugra9]

Done. I refactored all my code performance-oriented and updated the documentation.

For current consumers of the overload feature this is going to make things much slower, since there's a lot more work that will happen on every call to an overloaded function. Some thoughts on how we could improve this:

• First do a check for argument length, if there's only one method that matches call it. Otherwise, do the expensive type checking.
• There's a lot of split/joining and string matching. I think not relying on strings and keeping things split will be more efficient (see some comments inline).

Last, please update the documentation.

[bugra9]

Hi @brendandahl, do you have any suggestions?

[erenkucuker]

Hi, is there any plan to merge it ?