New subject: [Boost-Users] Template class static boost::mutex initialization !?!?!

17 Oct 2002

      Hello everyone,

i'm currently trying to implement a thread safe singleton using 
template. In the class I need to use a boost::mutex in order to protect 
access to the singleton pointer.
The problem i'm currently encountering is that I need to initialize this 
static boost::mutex, but how !?!?!?!

I tried using a pointer to a mutex and initialize it to null but that 
didn't work. I also tried to new it in the initialization but that 
failed too. :(

Can someone help me on this one ???

Thanks in advance for any help.

Luc.

P.S. I'm using boost 1.29 :)

P.S.S Here is my current class definition : (A link to where I got this 
implementation : 
http://www.drizzle.com/~scottb/publish/gpgems1_singleton.htm)

template <typename T>
class ThreadSafeSingleton
{
   static T* d_ThreadSafeSingleton;
   static boost::mutex d_mutex;

public:
   ThreadSafeSingleton()
   {
      assert(!d_ThreadSafeSingleton);
      int offset = (int)(T*)1 - (int)(ThreadSafeSingleton <T>*)(T*)1;
      d_ThreadSafeSingleton = (T*)((int)this + offset);
   }
   ~ThreadSafeSingleton()
   {
      assert(d_ThreadSafeSingleton);
      d_ThreadSafeSingleton = 0;
   }

   static T& GetSingleton(void)
   {
      boost::mutex::scoped_lock scoped_lock(d_mutex);
      assert(d_ThreadSafeSingleton);
      return *d_ThreadSafeSingleton;
   }

   static T* GetSingletonPtr(void)
   {
      boost::mutex::scoped_lock scoped_lock(d_mutex);
      return d_ThreadSafeSingleton;
   }
};

template <typename T> T* ThreadSafeSingleton <T>::d_ThreadSafeSingleton = 0;

Template class static boost::mutex initialization !?!?!

Luc Bergeron

Luc Bergeron

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