I have a class that provides a shared_ptr number.  At the end of the number's life cycle it should be placed back on a list of available numbers.  The shared_ptr's custom deleter function looks like what I need.  I'm able to get a free function to compile as the deleter just fine.  In trying to use a class member function as the custom deleter I've run into compile errors.  I'm not sure where I'm going wrong.  I know the custom deleter need to be copy constructible and I'm probably breaking some assumed requirement.  Any help on what I'm doing wrong would be appreciated.
Ryan