CODEWITHSUNDEEP
c++c++11move-semanticsassignment-operator
Etay
Etay

Reputation: 83

Separating copy/move assignment operator

I've read here: What are move semantics?, under secondary title: Special member functions, the reasons why we should unify both copy assignment operator & move assignment operator into a single move\copy assignment operator,

but what if we wish to forbid copying or moving? should in this case I indicate "deleted" on the forbidden constructor and implement the other? (i.e. separating between the two).

If so, what is the proper way to do it?

Upvotes: 0

Views: 134

Answers (1)

Miles Budnek
Miles Budnek

Reputation: 30494

If you want to create a class that is movable but not copyable, you should implement the move constructor and mark the copy constructor as deleted.

The copy-and-swap pattern still works (more of a move-and-swap, really). Since the parameter can only be move constructed, only move assignment will be available.

class MyClass
{
    MyClass(MyClass&& other) {
        // Do your move here
    }
    MyClass(const MyClass& other) = delete;

    MyClass& operator=(MyClass other) {
        // You can still use copy-and-swap (move-and-swap, really)
        // Since MyClass is non-copyable, only move assignment will be available
    }
};

Or you could just create a move assignment operator (MyClass& operator=(MyClass&& other)) instead. The default copy assignment operator will be implicitly deleted if you declare a move constructor.

Upvotes: 2

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