Question

I know this is possible but my inexperience with C++ limits me. What I want to do is have some system were I can add update() methods to certain classes and have all the update methods in the program be called every frame.

Unity3D users may be familiar with this. But how does the program know to call every Update() method when there are an undetermined amount of them in undetermined classes.

I suppose it is a system to dynamically call functions throughout the program.

Answer 1

Derive all the classes that have this Update method from an abstract class, then put pointers to all the variables for which you want this method to be called in some kind of vector.

Here’s a rudimentary example:

class Updatable
{
public:
    virtual void update() = 0;
};

class SomeClass : public Updatable
{
public:
    virtual void update()
    {
        printf("update for SomeClass was called\n");
    }
};

class AnotherClass : public Updatable
{
public:
    virtual void update()
    {
        printf("update for AnotherClass was called\n");
    }
};

int main()
{
    Updatable* v[10];
    int n = 0;
    SomeClass a, b;
    AnotherClass c, d;
    v[n++] = &a;
    v[n++] = &b;
    v[n++] = &c;
    v[n++] = &d;

    for (int i = 0; i < n; i++)
        v[i]->update();
}