Move Constructor with no pointers

Question

I know this question might seem very very basic. But I just can't find anywhere an example of a move constructor with no pointers.

I have a class that holds a vector object variable. Not a pointer to one. So my question: Does this mean that I have no need in a move constructor? Or is my implementation wrong and I should be using a pointer to a vector and then use a move constructor?

Thank you

Answer 1

If your class contains movable objects (such as a vector), then just let the compiler generate the implicit move operations. They will do the right thing, moving each subobject.

You'll only need to write your own if you're juggling raw pointers to dynamic objects, or other unmanaged resource handles, yourself. The best approach is to have a correctly copyable/movable object (such as a container, smart pointer, or other RAII class) to manage each of these; then a complex object built by composing these will implicitly have the correct copy/move semantics.

(As noted in the comments: if your class declares its own destructor, or copy operations, then it won't get implicit move operations; you'll need to define your own. But if you follow the advice above, composing it from correctly managed types that don't need any special handling, then you shouldn't need to declare any of these things.)

Answer 2

Move constructor follows similar guidelines as copy constructors. It is required when your class holds members by pointer or other fragile data fields (sockets, db connections etc), so that automatically generated one would possibly mess up the memory layout by deleting the same object twice. So if you don't have any pointer fields, you don't have to write move constructor.