Hi All,

I have problem implementing the operator!= in a set class deriving from an abstact one. The code looks like this:

class Abstract
{
  public:
     //to make the syntax easier let's use a raw pointer
     virtual bool operator!=(const Abstract* other) = 0;
};

class Implementation
{
    SomeObject impl_; //that already implement the operator!=
  public:
    bool operator!=(const Abstract* other)
    {
      return dynamic_cast<Implementation*>(other)->impl_ != this->impl_;
    }
};

This code works but it has the drawback to use dynamic_cast and I need to handle error in casting operation.

This is a generic problem that occur when a function of a concrete class it is trying to using some internal information (not available at the abstract class level) to perform a task.

Is there any better way to solve this kind of problem?

Cheers