Parametized Constructor Not an Copy one

问题

Say we have a class A that contains as a member of the same class:

Class A{
   const A &a;
}

I want to create a parametized constructor that passed the value of that member, but I do not want to define the copy constructor of the class.

A(const A& memberA): a(memberA)     {}

How could indicate the compiler such thing?

Thanks

回答1:

A constructor that can take just a reference to the class it constructs is a copy constructor, whether you want it to be one or not. Copy constructors are defined thus:

A non-template constructor for class X is a copy constructor if its first parameter is of type X&, const X&, volatile X& or const volatile X&, and either there are no other parameters or else all other parameters have default arguments.

You could declare it explicit to restrict how the class can be copied (preventing A a = A() for example), but it's still a copy constructor as long as it has that signature.

回答2:

You can define this constructor as explicit.

(That's a good rule for all constructors that can be called with one parameter.)

来源：https://stackoverflow.com/questions/13413419/parametized-constructor-not-an-copy-one