I've looking for how to cast class member to C-style callback.
Recentrly i found answer with special bind hack allows to bind class members to C-style callbacks:
https://stackoverflow.com/a/39524069/5405443
I have this working code to bind function MyClass::f to C function f: But i want to avoid explicit passing cb_type as template parameter to c_bind function. In provided example CB has type void (*)(int) and Func template parameter has void (MyClass::*)(int) type.
template<typename CB, typename Func, typename... Params>
CB* c_bind(std::_Bind<Func(Params...)> function) {
return Callback<typename ActualType<CB>::type, __COUNTER__, Func>::getCallback(function);
}
typedef void (cb_type)(int);
class MyClass {
public:
void f(int x) {
std::cout << "Hello from MyClass::f(int), value: " << x << std::endl;
}
};
int main() {
MyClass mc;
auto f = c_bind<cb_type>(std::bind(&MyClass::f, mc, std::placeholders::_1));
// ^ how to avoid explicit callback type declaration here?
f(10);
return 0;
}
Also i found this piece of code (https://gist.github.com/vikchopde/73b62314379f733e8938f11b246df49c) for "unwrapping" some kind of functions.
bool ok = fu::is_unwrappable<decltype(&MyClass::f)>::value; // always false
// fu::unwrap_function<decltype(&MyClass::f)>::type::function_ptr blah; // won't compile
but it won't work by unknown to me reason.
My question is there any workaround to extract return type and args list from type with class-memeber pointer like void (MyClass::*)(int) and contruct C-like type void (*)(int) ?
Thank you for any help!
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