Can operator= may be not a member?

Question

Having construction in a form:

struct Node
{
Node():left_(nullptr), right_(nullptr)
{ }
int id_;
Node* left_;
Node* right_;
};

I would like to enable syntax:

Node parent;
Node child;
parent.right_ = child;

So in order to do so I need:

Node& operator=(Node* left, Node right);

but I'm getting msg that operator= has to be a member fnc; Is there any way to circumvent this restriction?

Answer 1

Operator =() must be a member. And you can't overload the meaning of assignment for pointers.

Answer 2

Why not just use parent.right_ = &child? Creating an overloaded operator that assigns a value-type to a pointer would, if possible, be a very bad idea. It would obfuscate what really happens and make the code much harder to understand for someone who reads it.

Well, you already accepted an answer, but anyway, you could do what the guys that wrote Boost.Format did and just choose some other operator that can be overloaded as non-member function and has a low potential of conflicts (they chose %). In my opinion this is slightly less obfuscating.

Answer 3

An automatic conversion from value to pointer creates lots of possibilites to make your code hard to understand.

If you still want to do it you can provide a conversion operator on your Node class:

operator Node* () { return this; }

Answer 4

Replace

parent.right_ = child;

with

parent.right_ = &child;

and it wil work;