Noah Roberts wrote:[color=blue]
> mlimber wrote:
>[color=green][color=darkred]
> > > I'm not that great with templates and don't fully grasp the subtleties
> > > of what I am trying to accomplish. Can I forward declare this template
> > > and use it? I would prefer to do so based on the typedefs, not the
> > > actual template.[/color]
> >
> > You can't forward-declare a typedef because it is just an alias for
> > some other type, not a type itself. You can forward declare a class
> > template as such:
> >
> > template<class T> class SomeClassTemplate;
> >
> > But, to forward declare a class template with default parameters, you
> > have to specify them in the forward declaration:
> >
> > template<ENUM X, int I = 0> class Generic;
> >
> > Then you can include perhaps just your typedefs. You'll end up with
> > something like this:
> >
> > enum ENUM { A, B };
> >
> > template<ENUM X, int I = 0> class Generic;
> >
> > typedef Generic<A> SomeTypeA;
> > typedef Generic<B> SomeTypeB;
> > typedef Generic<A,1> SomeTypeBad;
> >
> > SomeTypeA* pa = 0;
> > SomeTypeB* pb = 0;
> > SomeTypeBad* pbad = 0;
> >
> > template<ENUM X, int I = 0> class Generic
> > {
> > public:
> > enum { val = I };
> > ENUM foo() const { return X; }
> > };[/color]
>
> So actually it might be best to create an "interface" header that had
> the forward declaration and the typedefs and include it in the headers
> of the clients. Then include the actual definition in sources.[/color]
If the forward declaration and typedefs are used widely, then sure.
[color=blue]
> I like templates but getting rid of the compile time dependencies with
> them can be tough...[/color]
Sometimes it's impossible. For instance, you can't (portably)
forward-declare STL containers such as std::vector since
implementations are permitted to attach as many extra template
parameters as they like, so long as they're given defaults.
Cheers! --M
