C++ invoke method from string

Question

There is in Qt such functionality: QMetaObject::invokeMethod(QObject * obj, const char * member, ...), which invokes method from string (member). How can I do the same (or similar)? Thanks)

Answer 1

You can't do this in pure c++, but you can read about reflection/introspect in c++ in this question

Answer 2

A similar thing can be achieved with a map<std::string, std::function<void()>>:

std::map<std::string, std::function<void()>> funs;
funs["hello world"] = [] () { std::cout << "hello world"; };
funs["hello world"]();

The question is how similar do you want it? How "native" should the call look like?. You can do things like:

void foobar(int, float);

...

    invoke("foobar", 5, 5.f);

but the implementation looks hacky and is non-trivial.

There is a related problem:

You can get pretty far with variadic templates and some template/virtual techniques. With the following codes, you'll be able to do something like:

std::string select_string (bool cond, std::string a, std::string b) {
    return cond ? a : b;
}

int main () {
    Registry reg;
    reg.set ("select_it", select_string);
    reg.invoke ("select_it", "1 John Wayne"));
    reg.invoke ("select_it", "0 John Wayne"));
}

i.e. where the argument list is dissected into a real argument list for a native function call. With variadic templates you can do a lot of things; I am not sure if you should.