auto ref

[dsimcha]

== Quote from Nick Sabalausky (a at a.a)'s article
> "dsimcha" <dsimcha at yahoo.com> wrote in message
> news:hgdpn2$t1c$1 at digitalmars.com...
> > == Quote from Nick Sabalausky (a at a.a)'s article
> >> Pardon my ignorance, but why is it that templated functions can't be
> >> virtual?
> >
> > This is an unfortunate consequence of compilation model leaking out into
> > language
> > design.  You're supposed to be able to subclass a base class even if you
> > don't
> > have the full source code to it.  Let's say we have:
> >
> > class A {
> >    void doStuff(T)(T arg) {}
> > }
> >
> > class B : A {
> >    void doStuff(T)(T arg) {
> >        writeln("In B.");
> >    }
> > }
> >
> > And then we do:
> >
> > B b = new B;
> > b.doStuff(1);
> >
> > The instantiation of B.doStuff() with an int would require that the vtable
> > for A
> > be updated to include doStuff!(int).  This is not possible if we also
> > allow base
> > classes to be compiled separately from derived classes and the code that
> > uses the
> > derived class.
> >
> > The only solution I see would be to completely get rid of separate
> > compilation.
> > For my personal use, since most of my projects are under 10k lines and
> > take a
> > negligible amount of time to compile anyhow, I'd be in favor of this.
> > However,
> > for larger projects or projects that require things to work based only on
> > interface, without access to the full source code, this is probably
> > impractical.
> But we already can't instantiate templates without the source anyway, so I
> don't see how doing that vtable update for A would create any additional
> requirements on source availability that we don't already have, regardless
> of whether or not the function is virtual. Either way, the issue of "Do I
> need to provide the source?" still boils down to just "Am I defining a
> public template?" and is not at all dependent on "Is this going to be
> externally subclassed?".

To clarify, the requirement is somewhat stronger than having the source.  A, B,
and all code that instantiates template methods of A or B would probably all have
to be compiled as one compilation unit to get the vtable layout right.