Question

I have a header file that looks something like the following:

class Model {
 private:
  struct coord {
    int x;
    int y;
  } xy;
 public:
  ....
 coord get() const {
  return xy;
 }
};

And in yet another file (assume ModelObject exists):

struct c {
 int x;
 int y;
 void operator = (c &rhs) {
   x = rhs.x;
   y = rhs.y;
 };
} xy;

xy = ModelObject->get();

The compiler throws an error that says there is no known covnersion from coord to c.
I believe it is because it doesn’t know about coord type because it is declared inside of a class header. I can get around that by declaring the struct outside of the class, but I was wondering if it is possible to do the way I am, or is this generally considered bad practice

Answer 1

You would need an implicit conversion operator for Model::coord to c. For information on how to do this, I recommend taking a look at C++ Implicit Conversion Operators.

Also, when you mentioned “It does not know the type because it is in a class”, you would use Model::coord as the struct type to the outside world (as long as coord is public, which in your current case it is not).