Reducing code duplication between operator= and the copy constructor

Question

I have a class that requires a non-default copy constructor and assignment operator (it contains lists of pointers). Is there any general way to reduce the code duplication between the copy constructor and the assignment operator?

Answer 1

There's no "general way" for writing custom copy constructors and assignment operators that works in all cases. But there's an idiom called "copy-&-swap":

 class myclass
 {
    ...
 public:
    myclass(myclass const&);

    void swap(myclass & with);

    myclass& operator=(myclass copy) {
        this->swap(copy);
        return *this;
    }

    ...
};

It's useful in many (but not all) situations. Sometimes you can do better. A vector or a string could have a better assignment which reuses allocated storage if it was large enough.