Thread: tricky: static int on template class;

Code:

#include <iostream>

class MultiCounter
{
public:
	static int multicounter;
};
	
int MultiCounter::multicounter;

template<class T>
class MyTemplate : public MultiCounter
{
public:
	static int counter;
};

template<class T>
int MyTemplate<T>::counter;

int main(void){

   std::cout << ++(MyTemplate<int>::counter) << std::endl;
   std::cout << ++(MyTemplate<float>::counter) << std::endl;
   
   //but
   
   std::cout << ++(MyTemplate<int>::multicounter) << std::endl;
   std::cout << ++(MyTemplate<float>::multicounter) << std::endl;

}

As you have probably guessed, MyTemplate<int> and MyTemplate<float> are completely different classes when compiled....so defineing a static varibale wont apply to both of those types......as normal though - there is a way around - derive the template from a non template class and hold your static member there

You define counter outside the class declaration as you would any static member...define it as above and you wont have a problem

Templates - tricky buggers

Fordy is right on the money (which is not unusual). You could also make a static global variable as your counter. The global should be a little more desirable unless there is something you are trying to do as far as encapsulation is concerned.

Well Fordy's solution does address what you are saying now whereas mine doesn't. Also you can put your macros into a header file.

myheader.h

Code:

#ifndef MY_HEADER_FILE
#define MY_HEADER_FILE


#define WNDCOUNTER(ClassName) int Window<ClassName>::s_instancecount=0;

#endif

Then using #include "myheader.h" in each c file.