UniqueObject.h

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#ifndef _utl_UniqueObject_h_
#define _utl_UniqueObject_h_

#include <sstream>
#include <utl/TypeId.h>
#include <utl/AugerException.h>


namespace utl {

  template<class T>
  class UniqueObject {
  public:
    static
    void
    EnsureUnique()
    {
      if (fgCounter != 1) {
        std::stringstream err;
        err << "Class " << TypeId<T>.Name() << " is not unique"
               " (" << fgCounter << " instances)!";
        throw utl::InitSequenceException(err.str());
      }
    }

  protected:
    // derived class can call ctor and dtor
    UniqueObject() { ++fgCounter; EnsureUnique(); }
    ~UniqueObject() { --fgCounter; }

    // this is only for testing purposes
    static void Reset() { fgCounter = 0; }

  private:
    static int fgCounter = 0;

  };

}


#endif