Shared Singleton across DLLs

[globos]

Hello,

I would like to have a Singleton class that ensures to have only one instance wherever the code flow is in a DLL or in the main program.
My Singleton class is like this:

template<class G>
class Singleton 
{
public:
  // Unique instance of type G.
  static G* instance ()
  {
    static G* _instance = Void;
    if (_instance == Void)
      _instance = new G;
    return _instance;
  }
};

My problem is that I have two different instances of a Singleton. One in my DLL and one in my main program.
In the main program :

int main ()
{
  Object* object = Singleton<Object>::instance ();
  cout << "address in main : " << object << endl;

  // Load the function test_in_dll() from the DLL and access the singleton inside...
  // Call the function :
  test_in_dll ();

  return 0;
}


void test_in_dll ()
{
  Object* object = Singleton<Object>::instance ();
  cout << "address in dll : " << object << endl;
}

It prints two different addresses.
Is it possible to have a real Singleton?

I'm using VC++ 6.0.

--
Globos

 

[RichardF]

Hi,

You can use #pragma data_seg in your DLL to share the same instance of the singleton. Note that this will also share the same data across all applications that use the Dll.

You can google on #pragma data_seg.


Hope this helps.
Rich.



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