[boost] Re: New Singleton Release

From: Martin (adrianm_at_[hidden])
Date: 2005-03-05 10:51:33

> Keep at least one global or static pointer to the singleton.  The global 
> pointer is different in concept than a real global instance, as it is 
> being used to control the moment of creation, rather than to provide a 
> global point of access.  You can hide the global pointer in an unnamed 
> namepace in some obscure source file if you want to make it really clear 
> that it isn't the access mechanism.

The problem is that I don't have a source files to put a global variable in. 

My library is a template that lives entierly in header files. At the moment I 
got a single cpp file that only contains the global variable. It works but it 
forces the library users to include the source file in their project so I 
would like to get rid of it.

The singleton seem to solve the problem but since the global variable isn't 
created until it is used it could happen that two threads create it at the 
same time. The global variable is constant so it is only the creation that 
needs locking. I could use a locking policy but it would be easier if I could 
just force creation at startup. 

> Disabling of the singleton's default copy constructor was intentional, 
> you can ignore or disable this warning.

Why does a singleton need a copy contructor?