Why use private copy constructor vs. deleted copy constructor in C++

Question

Why would one prefer to use a private copy constructor over deleting the copy constructor in C++?

E.g.:

class Entity { private: Entity(const Entity &copy) // <== private copy constructor { /* do copy stuff */ } public: /* more code here... */ }

As opposed to:

class Entity { public: Entity(const Entity &copy) = delete; // <== copy constructor deleted /* more code here... */ }

Related questions that don't quite answer what I'm asking:

private copy ctor can be used in other member functions. if resource of the class is unique, the delete can ne used. for example, you can make copy ctor private, and provide a public clone function to outside — rsy56640
– rsy56640, Commented Nov 3, 2018 at 1:32

Slava · Accepted Answer · 2018-11-03 01:36:00Z

3

2 possible reasons:

you cannot use C++11 or later
you need objects of the class to be copyable by methods of the class or it's friends, but not by anything else

answered Nov 3, 2018 at 1:36

44.4k2 gold badges54 silver badges100 bronze badges

Sign up to request clarification or add additional context in comments.

2 Comments

could you please provide an example construct of where you might want an instance to be able to copy, where you wouldn't want outsiders to do so?

@camercu A linked list node. The only classes who should be able to create a node are nodes and the linked list, a friend of the node.