Effective C + +-----clause 12: Don't forget every ingredient when copying an object

The copying function should ensure that all member variables within the object and all base class components are copied.

Do not attempt to implement another copying function with one of the copying functions. Common functions should be put into the third function and called together by two coping functions. If you find that your copy constructor and the copy assignment operator have similar code, the practice of eliminating duplicate code is to create a new member function to call both. Such functions are often private and often named Init. This strategy can safely eliminate code duplication between the copy constructor and the copy assignment operator.

Effective C + +-----clause 12: Don't forget every ingredient when copying an object