class A
{
void (*varFunc)();
public:
inline void Func()
{
varFunc();
}
A(void (*myFunc)()) : varFunc(myFunc)
{
}
};
class B : public A
{
void myFunc()
{
cout<<"Func"<<endl;
}
public:
B() : A(&myFunc)
{
}
};
int main()
{
B Test;
Test.Func();
}
Function Pointer Problem
Author
The signature for a class method does not match that for a non-class function. The difference is one of calling convention - __thiscall vs __stdcall - which means that they pass their parameters differently. A workaround is to make the class method static, but that can introduce certain constraints.
A more robust solution is to use a functor or function object:
If you make the Functor class an interface, or at least a base class, then all classes derived from it can be invoked through polymorphic dispatch.
For reference, though: www.function-pointer.org.
A more robust solution is to use a functor or function object:
struct Functor{ Functor() { // any initialization } void operator () () { // do whatever }};...Functor f;..f(); // invokes functor just like a function pointerIf you make the Functor class an interface, or at least a base class, then all classes derived from it can be invoked through polymorphic dispatch.
For reference, though: www.function-pointer.org.
Hmm...I'm not really sure what you're trying to do with varFunc(myFunc) in the constructor for class A.
Are you...trying to set it to the value of myFunc? I didn't think that you could do that with function pointers. But then again, I just recently learned how to use them, so many of the uses are, uh...Greek to me.
Still, I'll try to help as much as I can here.
Are you...trying to set it to the value of myFunc? I didn't think that you could do that with function pointers. But then again, I just recently learned how to use them, so many of the uses are, uh...Greek to me.
Still, I'll try to help as much as I can here.
Author
lol, I actually used functors without knowing it for my problem. See I had this problem a while ago, but I never bothered to ask about it until now. So yeah, the code I wrote as it turns out is basically just used a functor and that works fine.
This topic is closed to new replies.
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