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

From: Luc Bergeron (bluc_at_[hidden])
Date: 2002-10-17 14:12:25

Never mind my previous  message... I found the solution after pressing 
the send button.

Sorry.

Luc.

Luc Bergeron wrote:

> 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) 
> <http://www.drizzle.com/%7Escottb/publish/gpgems1_singleton.htm%29>
>
> 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;
>
>
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