Re: templates & classes
John Carson wrote:
"Pete Becker" <pete@versatilecoding.com> wrote in message
news:FrSdnXYRvKafzkLYnZ2dnUVZ_vWtnZ2d@giganews.com
Fei Liu wrote:
Pete Becker wrote:
Fei Liu wrote:
Pete Becker wrote:
Fei Liu wrote:
The description of the OP's problem requires that 2 classes do
not share the storage of those static members. In this case,
derivation won't work.
Of course it will. The things that aren't shared don't go in the
base class.
It will what?
"In this case, derivation won't work."
"Of course it will.
What, specifically, do you claim "won't work"? Whatever is defined
in the base class is part of the base class, and whatever is
defined in the derived classes is part of the derived classes. So
if you want the derived classes to hold something in common, put it
in the base class. If you want the derived classes to hold
independent things, put them in the derived classes. The result is
that the derived classes both have whatever is in the base class,
and each has whatever is defined for it.
Clearly you don't understand the OP's spec, hint it's a device
driver. Your logical representation fails to meet the requirement of
the physical model.
On the contrary: I have read it carefully, and suggested an approach
that will do exactly what he said he wants.
Once again: what, specifically, do you claim "won't work"? No more
handwaving. Point out the exact problem, so that readers of this
thread will have a chance at understanding what it is that you think
can't be done through inheritance.
Speaking for myself, I didn't think much about the OP's spec, I just wanted
to answer the OP's question (just stating a fact here, not making a case).
Indeed. And you may have noticed that I didn't jump in and insist that
you're wrong. In fact, I suspect that a template may be the right answer
to the question that wasn't asked. But given the original problem
statement, all that's needed is to hoist one data member and one member
function into the derived class, and that doesn't call for a template.
Low-level design follows from actual specifications, not from guesses.
--
-- Pete
Roundhouse Consulting, Ltd. (www.versatilecoding.com)
Author of "The Standard C++ Library Extensions: a Tutorial and
Reference." (www.petebecker.com/tr1book)
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