Question

I have 2 class:

    class Request
    {
      KeyValuePair* dimension;
    };

    class Response
    {
      KeyValuePair* dimension;
    };

    class KeyValuePair
    {
        public:
        hash_map<string, string> hmap;
    };

in one of the method, I want to populate the Response.dimension with Request.dimension but I want the Request.dimension pointing to a different address from Response.dimension?

I don’t want any change Response.dimension which also affect Request.dimension.

Is there a way to do that?

void Transformation::applyTransformations(const Request& req, Response& res)
{
   res.dimension = req.dimension; // WRONG. Pointing the same address.
}

Answer 1

Yes, of course:

*(res.dimension) = *(req.dimension);

Note that if KeyValuePair is not a POD type, you should define the assignment operator (operator =), as it will get called during the assignment. If you don’t, the compiler-generated one will be called.

You should also check if res.dimension is properly allocated, if not, use the copy constructor:

if ( res.dimension )
   *(res.dimension) = *(req.dimension);
else
   res.dimension = new KeyValuePair(*(req.dimension));