Template Member function undfined

[Xillez]

I have a problem with undefined templated member function used in main.

Error:
"CMakeFiles/Framework.dir/source/src/main.cpp.o: In function `main':
main.cpp:(.text +0x33): undefined reference to `unsigned int EntityMgr::crea teEntity<Entity >()'"

Can someone please help me understand why the EntityMgr::crea teEntity function is undefined from main?

Current setup (simplified):

//EntityMgr.hpp
#include "Entity.hpp"
class EntityMgr
{
    template<typename>
    unsigned int createEntity();
}

// Entity.hpp:
class Entity
{
    //
};

EntityMgr.cpp:

template<typedef Class>
unsigned int EntityMgr::createEntity()
{
    ...
}

main.cpp:

#include "EntityMgr.hpp"

int main()
{
    EntityMgr entityMgr;
    entityMgr.createEntity<Entity>();  <--- Problem line.
    return 0;
}

[weaknessforcats]

I fixed your code. Look how I parameterize template<> and compare to the original code. Using "typedef" or "typename" is bogus because those are not types. Using "class T" defines T as a type. That is the T used by the precompiler to generate your specialized template function.

Also be clear on these terms: A template function is the function generated by the precompiler from a function template.

These two terms are often mixed up and this can lead to confusion when trying to understand how things work.

//EntityMgr.hpp
//#include "Entity.hpp"
class EntityMgr
{
public:

	template<class T>
	unsigned int createEntity();
};

// Entity.hpp:
class Entity
{
	//
};

template<class T >
unsigned int EntityMgr::createEntity()
{
	return 0;  //for compile only
}

//#include "EntityMgr.hpp"

int main()
{
	EntityMgr entityMgr;
	entityMgr.createEntity<Entity>();  //<-- - Problem line.
		return 0;
}