In an earlier question, I asked asked class template inheritance in C++.
I now have an extra level to add!
Consider the following code. (Assume the member definitions are present and accurate)
namespace Game
{
namespace Object
{
template<typename T>
class Packable
{
public:
/**
* Packs a <class T> into a Packet (Packet << T)
* Required for chaining packet packing
*************************************************/
virtual sf::Packet& operator <<(sf::Packet& packet) = 0; // Work-horse, must be defined by child-class
friend sf::Packet& operator <<(sf::Packet& packet, T &t);
friend sf::Packet& operator <<(sf::Packet& packet, T *t);
/**
* Unpacks a <class T> from a Packet (Packet >> T)
* Required for chaining packet unpacking
*************************************************/
virtual sf::Packet& operator >>(sf::Packet& packet) = 0; // Work-horse, must be defined by child-class
friend sf::Packet& operator >>(sf::Packet& packet, T &t);
friend sf::Packet& operator >>(sf::Packet& packet, T *t);
/**
* Unpacks a <class T> from a Packet (T <<= Packet)
* Returns the <class T> for convienence
*************************************************/
//friend T& operator <<=(T t, sf::Packet& packet); // Returning reference to cut down on copying (they're already passing us our own copy)
friend T& operator <<=(T &t, sf::Packet& packet);
friend T* operator <<=(T *t, sf::Packet& packet);
};
}
}
And this Ship class inherits from Game::Object::Packable
class Ship : public Game::Object::Base<Ship>, public Game::Object::Packable<Ship>
{
public:
Ship( void );
//...
// For packing and unpackinng packets
sf::Packet& operator <<(sf::Packet& packet);
sf::Packet& operator >>(sf::Packet& packet);
}
What we're left with is the following error.
(null): "Game::Object::operator<<(sf::Packet&, Ship*)", referenced from:
I've come to the conclusion that it must have something to do with the use of namespaces. What is the solution to this if I wanted to retain the namespaces?
Here is an excerpt of the method definitions. Do I have to dereference the namespace? (I don't think that even means anything haha)
/**
* Packs a <class T> into a Packet (Packet << T)
* Required for chaining packet packing
*************************************************/
template<class T>
sf::Packet& operator <<(sf::Packet& packet, T *t)
{
// Call the actual one, but basically do nothing... this needs to be overrided
return packet << *t;
}
template<class T>
sf::Packet& operator <<(sf::Packet& packet, T &t)
{
// Call the pointer one, but basically do nothing... this needs to be overrided
return packet << &t;
}
// ... other definitions etc.
