Unresolved Externals problem

[eNergizer]

Here's the errors:

Error 3 error LNK2019: unresolved external symbol "public: class Core * __thiscall Handle<class Core>::operator->(void)const " (??C?$Handle@VCore@@@@QBEPAVCore@@XZ) referenced in function _main C:\Users\DJ\documents\visual studio 2010\Projects\14.1 - A Generic Handle Class\14.1 - A Generic Handle Class\main.obj
Error 4 error LNK2019: unresolved external symbol "public: class Handle<class Core> & __thiscall Handle<class Core>::operator=(class Handle<class Core> const &)" (??4?$Handle@VCore@@@@QAEAAV0@ABV0@@Z) referenced in function _main C:\Users\DJ\documents\visual studio 2010\Projects\14.1 - A Generic Handle Class\14.1 - A Generic Handle Class\main.obj
Error 5 error LNK2001: unresolved external symbol "public: class Handle<class Core> & __thiscall Handle<class Core>::operator=(class Handle<class Core> const &)" (??4?$Handle@VCore@@@@QAEAAV0@ABV0@@Z) C:\Users\DJ\documents\visual studio 2010\Projects\14.1 - A Generic Handle Class\14.1 - A Generic Handle Class\Student_info.obj
Error 6 error LNK1120: 2 unresolved externals C:\Users\DJ\documents\visual studio 2010\Projects\14.1 - A Generic Handle Class\Debug\14.1 - A Generic Handle Class.exe 1


Handle.h

#ifndef GUARD_Handle_h
#define GUARD_Handle_h

#include "Grad.h"

template<class T> class Handle
{
public:
	Handle(): p(0) { }
	Handle(const Handle& s): p(0) { if (s.p) p = s.p->clone(); }
	Handle(T* t): p(t) { }
	Handle& operator=(const Handle&);
	~Handle() { delete p; }

	operator bool() const { return p; }
	T& operator*() const;
	T* operator->() const;

private:
	T* p;
};

static bool compare_Core_handles(const Handle<Core>& s1, const Handle<Core>& s2)
{
	return s1->name() < s2->name();
}

#endif 

Handle.cpp

#include "Handle.h"
#include <stdexcept>

using std::runtime_error;

template <class T> Handle<T>& Handle<T>::operator=(const Handle& rhs)
{
	if (&rhs != this) {
		delete p;
		p = rhs.p ? rhs.p->clone() : 0;
	}
	return *this;
}

template <class T> T& Handle<T>::operator*() const
{
	if (p) return *p;
	throw runtime_error("unbound Handle");
}

template <class T> T* Handle<T>::operator->() const
{
	if (p) return p;
	throw runtime_error("unbound Handle");
}

[eNergizer]

I fixed it by putting all of the functions of Handle.cpp after the class definition in Handle.h

Does anyone know how to make it work by using Handle.cpp?

[ne555]

explicit template instantiation http://www.cplusplus.com/forum/articles/14272/