Re: [libcvd-members] gvars3 Makefile.in configure configure.ac gvars...

[Edward Rosten]

On Wed, 20 Feb 2008, Ethan Eade wrote:

> > > template <int DUMMY> double HoldsGlobal::global = 3.14;
> > > //end code
> > >
> > > Then you use HoldsGlobal<>::global.  The linker is required to treat it
> > > as a weak symbol -- i.e., there will be exactly one instance common to
> > > all translation units when linked.
> > The other problem is the order of calling global constructors. The
> > standard is rather unhelpful about this.
> Yes, trickier.

One trick is the very closely relates trick to the one above with the 
lazy instance method:

template<int Dummy=0> class foo
{
    foo(){}


    static foo* inst=0;

    public:

    foo& instance()
    {
        if(!foo)
                inst = new foo();

        return *foo;
    }
};

The first thing to use it causes it to be initialized. The trouble is the 
rather irritating syntactic overhead of having to do foo::instance(). 
instead of foo. everywhere.

The trouble with GVars is that introducing new syntax would break too much 
old code. I suppose I could gut GUI, make it a trivial class with no state 
and make all the methods be thin wrappers to 
a_new_GUI_implementation::instance().blah()

Ick.

It does seem to me that there is little point in having GUI be a non 
singleton, since the GVars database is a singleton.

-Ed