Question

I have a program that defines changes the target function of a function pointer from within the function being called by said pointer, like so:

void increment(int&);
void superincrement(int&);

void (*fooncrement)(int&);

int main() {
    int j = 0;
    fooncrement = increment;
    while (true == true) {
        fooncrement(j);
    }
}

void increment(int& i) {
    static int counter = 0;

    i++;

    if (counter > 7)
        fooncrement = superincrement;
    counter++;
}

void superincrement(int& i) {
    i += 23;
}

A quick run through MSVC’s debugger shows that the program more or less works as expected. However, are there are any problems not immediately obvious here that might manifest if I tried something like this in a more complex environment?

Answer 1

This is well-defined.

In fact, this technique is often used to implement state machines.