Hi
When is it sufficient ot leave auto generated copy /copy assignment operator and when is it not? Could someone be so kind to post a small example for each situation since i don't quite get this ?? (it is not necessary for it to be a code just a conceptual case and what can go wrong)
thank you so much
baxy
Consider the member variables: do they all do their own memory management? Generally, if you see a (non-smart) pointer in there, it is an indicator that the class may need to define the copy constructor and copy assignment operator (or declare them private). Likewise, it is a hint that you may need to define the destructor (read up on the rule of three, though this rule has expanded somewhat with the advent of C++11).
Look up a C++ Reference and learn How To Ask Questions The Smart WayOriginally Posted by Bjarne Stroustrup (2000-10-14)
Ideally the only time you need an explicit copy operations is when your class is a resource. That could mean it's a container that manages it's own memory, or a wrapper around a file or something fetched over a network. As laserlight says, a destructor is also likely needed.
Raw pointers are an indicator of this; if a class has a raw pointer, it's probably managing whatever it points to as a resource. If the class does a lot of other things, it would be good design to separate the code that manages the resource into it's own class.
Another case I've encountered that needs explicit copy constructors is when the class is copyable, but contains parts that cannot be copied. However, these cases are rare.
It is too clear and so it is hard to see.
A dunce once searched for fire with a lighted lantern.
Had he known what fire was,
He could have cooked his rice much sooner.
