このエラーがあります:
Undefined symbols for architecture x86_64:
  "my::Queue<int>::Queue()", referenced from:
      _main in ccdwI88X.o
ld: symbol(s) not found for architecture x86_64
collect2: ld returned 1 exit status
このコードの場合'main.cpp':
#include "Queue.hpp"
int main()
{
  my::Queue<int> myqueue;
  return 0;
}
'Queue.hpp':
#ifndef QUEUE_HH__
#define QUEUE_HH__
namespace my
{
  template <typename T>
  class Queue
  {
  public:
    Queue();     
  };
}
#endif
および'Queue.cpp':
#include "Queue.hpp"
template <typename T>
my::Queue<T>::Queue() 
{
}