I have a class that I can have many instances of. Inside it creates and initializes some members from a 3rd party library (that use some global variables) and is not thread-safe.

I thought about using static boost::mutex, that would be locked in my class constructor and destructor. Thus creating and destroying instances among my threads would be safe for the 3rd party members.

class MyClass

{

  static boost::mutex mx;



  // 3rd party library members

public:

  MyClass();

  ~MyClass();

};



MyClass::MyClass()

{

  boost::mutex::scoped_lock scoped_lock(mx);

  // create and init 3rd party library stuff

}

MyClass::~MyClass()

{

  boost::mutex::scoped_lock scoped_lock(mx);

  // destroy 3rd party library stuff

}

I cannot link because I receive error:

undefined reference to `MyClass::mx`

1. Do I need some special initialization of such static member?

2. Is the whole conception of static mutex wrong?