Object* a = new Object();
Object* b = a;
Is there a way in the Object class to know that 'b = a' happened? I tried overloading the operator= but it didn't seem to fire.
3 Answers
You overloaded the operator for Object not for Object*. You cannot overload operators for primitive pointers.
You will need to write a wrapper that simulates pointers but tracks operations. Perhaps you're looking for a smart pointer like shared_ptr? It implements reference counting like it seems you're trying to do.
9 Comments
user441521
Bummer. I am looking for a smart pointer but I don't like wrapping pointers so was playing with possible alternatives. So no way to know when one pointer is set to another huh? That sucks. Thanks.
paulm
Oh is that actually true about not being able to overload operator = for Object*? I thought that was possible?
Corbin
@user441521 Not realistically. A wrapper is your only reasonable option. Luckily the wrapper can be fairly transparent since * and -> can be overloaded to act on the wrapped pointer.
paulm
I don't see why you need to know when the assignment happens?
Corbin
Another thing to keep in mind is that pointers are easy to overuse in C++ if you're not careful. You might want to step back at some point, decide why you're using a shared pointer and decide if it's correct. A shared pointer should only be used if multiple objects truly do own (as in are responsible for it's life cycle) one object. That tends to be a fairly rare situation in most programs. If you're just using smart pointers for easy life time management, than automatic lifetime (i.e. variables on the stack) and RAII are probably a better option.
|
Is this really what you want to do?
Seems to me that you want to copy the value of a to b?
I.e:
Object* b = *a;
Otherwise you are just setting b to point to a. You'd have to overload operator = for Object* rather than operator = as part of Object for a const Object&. Unless you really do want to copy the pointer in which case what you have is fine.
Note that overloading operator = for Object* is aparrently not possible! I doubt this is actually what you where really trying to do anyways.
Comments
I don't think this is going to invoke the copy constructor of Object class or use the '=' operator of Object class. It's just the assignment between two pointers of Object. So even you has overload the Object's '=' operator, which is not invoked in this case, you got nothing fired.
std::shared_ptr?