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

[Georg Klein]

Ethan Eade wrote:
> > > You can always use the template trick, which requires the linker to
> > > ensure that only one instance is created:
> > > // code in a header:
> > > template <int DUMMY=0> struct HoldsGlobal {
> > >    double global;
> Should read "static double global;"
> > > };
> > >
> > > 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.

Unrelated to GVars, but while we're on the topic of statics and singletons: 
One mechanism for a singleton class foo is to have

foo& foo::getinstance()
{
   static foo f;
   return f;
}

but the page where I read about this said something along the lines of ``use 
only when single-threaded.'' Why might that be?