Re: Would templates make this simpler?

From:

"David Ching" <dc@remove-this.dcsoft.com>

Newsgroups:

microsoft.public.vc.mfc

Date:

Sat, 28 Apr 2007 11:55:13 -0700

Message-ID:

<RaSYh.3238$uJ6.537@newssvr17.news.prodigy.net>

"Doug Harrison [MVP]" <dsh@mvps.org> wrote in message
news:kav6331qpha8a5t8s6a62hfkni89cmls37@4ax.com...

FWIW, you'll find far more template expertise in
microsoft.public.vc.language and far, far more in comp.lang.c++.moderated.

I know, but this is a simple template issue and I'd rather ask my buddies
here.

It's not going to work since templates are a compile-time mechanism, and
flag isn't known until run-time. Since you want to create CDerived
instances, it's not the right approach anyway. I guess the closest you
could come using templates is to do something like this:

template<bool X> class Derived;

template<>
class Derived<true> : public CBase
{
...
};

template<>
class Derived<false> : public CBase
{
...
};

CBase* p1 = new Derived<true>;
CBase* p2 = new Derived<false>;

But that still doesn't solve your problem, because your bool value isn't
known until run-time.

OK, thanks. This isn't what I want at all. My understanding is that
templates can replace inheritance in some instances. I guess it would work
if I did something like

template<bool X> class Base
{
void <bool X>Method1();
};

The syntax is probably bad, but the idea is to get rid of the Derived
classes and just put the multiple functionality within Method1() of the
various templateized Base.

But even if that got rid of the Derived classes, you are right that the if()
to instantiate the correct class would remain. I can't see that using
templates would be an advantage for this type of situation.

-- David