How to write a function pointer to a function returning a function pointer to a function?

Question

I want to assign a function\'s address to a function pointer, but the function to be addressed returns a function pointer with the same signature as itself, causing it to recurs

Answer 1

I suspect what you are trying to do is a more complex version of something like this:

typedef MainLoop *MainLoop(); // not legal

extern MainLoop* main_loop_1();
extern MainLoop* main_loop_2();

MainLoop* main_loop_1()
{
    // do some work here
    return main_loop_2;
}

MainLoop* main_loop_2()
{
    // do some work here
    return main_loop_1;
}

int main()
{
    MainLoop f = main_loop_1;

    for (;;) {
      f = f();
    }
}

A workaround is to wrap the function pointer in a struct:

struct MainLoop {
    MainLoop (*function_ptr)(); // legal
};

extern MainLoop main_loop_1();
extern MainLoop main_loop_2();

MainLoop main_loop_1()
{
    // do some work here
    return {main_loop_2};
}

MainLoop main_loop_2()
{
    // do some work here
    return {main_loop_1};
}  

int main()
{
    MainLoop f{main_loop_1};

    for (;;) {
       f = f.function_ptr();
    }
}