Per thread singleton

[Soleng]

I would like to have a singleton class along the lines of the Meyer's Singleton but which is private to a single thread. The singleton should automatically destroy itself when the thread dies.

Any suggestions are appreciated!

Harald

[jencas]

Make the Singleton a member of your thread class

[_adam_]

From the Design Patterns book (Gamma, Helm, Johnson, Vlissides):

SINGLETON
-------------------
Intent
Ensure a class has only one instance, and provide a global point of access to it.

As a singleton is globally unique, I assume that what you require would simply be an instance of your object inside the thread class (that isn't based on the Singleton design pattern).

Regards,
Adam

[Soleng]

I would like the class to have only one instance per thread.
There should be a global access to this instance within the thread.

Harald

[_adam_]

The Singleton object instance is globally unique for the class you are making a Singleton.

By nature it had a single instance per application.

You would have to create several duplicate objects to achieve what I think you're after.

You could however have multiple objects stored in a static map within your "Singleton" and access these via some sort of thread ID.
For example:

class SingletonClass
{
public:
    static void CreateInstance( unsigned int uiThreadID );
    static SingletonClass* Instance( unsigned int uiThreadID );
    static void DestroyInstance( unsigned int uiThreadID);

    // other stuffs...

private:
    static std::map<unsigned int, SingletonClass*> m_smSingletonMap;

    // other stuffs...

};

However, you'd need to create and kill the object manually on thread creation and death respectively.

I still think you'd be better served by a single object instance as part of your thread class.

Adam.