Re: Singleton MFC Extension DLL

From:
MFDonadeli <mfdonadeli@gmail.com>
Newsgroups:
microsoft.public.vc.mfc
Date:
Thu, 7 Jan 2010 10:05:18 -0800 (PST)
Message-ID:
<df870352-d22e-451e-b288-010a7287ce45@26g2000yqo.googlegroups.com>
On 7 jan, 16:01, Ajay Kalra <ajayka...@yahoo.com> wrote:

On Jan 7, 12:54 pm, MFDonadeli <mfdonad...@gmail.com> wrote:

Hi.

I declare a singleton on a MFC extension DLL, like this:

<pre>
//header file: SingleTon.h
class AFX_EXT_CLASS CMySingleton
{
public:
  static CMySingleton* Instance()
  {
        if(!singleton)
                singleton = new CMySingleton();
    return singleton;
  }

  int a;

// Other non-static member functions
private:
  CMySingleton() {}; =

        // Private

constructor
  CMySingleton(const CMySingleton&); =

// Prevent copy-

construction
  CMySingleton& operator=(const CMySingleton&); // Preve=

nt

assignment
  virtual ~CMySingleton() {};

  static CMySingleton* singleton;

};

And in a cpp file I code the following line:

CMySingleton* CMySingleton::singleton = NULL;
</pre>

Code 2:
<pre>
CMySingleton *a;

a = CMySingleton::Instance();
</pre>

The problem is when I code "code 2" in a Regular Dll, all works fine,
but when I code "code 2" in another MFC extension DLL gives an error:

<pre>
unresolved external symbol "private: static class CMySingleton*
CMySingleton::singleton" (?singleton@CMySingleton@@0PAV1@A)
</pre>

Any idea?


Are you sure you are including the correct .lib file in MFC extesion
DLL where you code2 sits?

--
Ajay


Yes, via Project Dependencies on VS 2008...

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