指向非静态成员函数的 C++ 函数指针(类成员)

Question

class Foo {
public:
    Foo() { do_something = &Foo::func_x; }

    int (Foo::*do_something)(int);   // function pointer to class member function

    void setFunc(bool e) { do_something = e ? &Foo::func_x : &Foo::func_y; }

private:
    int func_x(int m) { return m *= 5; }
    int func_y(int n) { return n *= 6; }
};

int
main()
{
    Foo f;
    f.setFunc(false);
    return (f.*do_something)(5);  // <- Not ok. Compile error.
}

我怎样才能让它工作？

Answer 1

 class A{
    public:
        typedef int (A::*method)();

        method p;
        A(){
            p = &A::foo;
            (this->*p)(); // <- trick 1, inner call
        }

        int foo(){
            printf("foo\n");
            return 0;
        }
    };

    void main()
    {
        A a;
        (a.*a.p)(); // <- trick 2, outer call
    }