Re: inheritance, list of objects, polymorphism
On Dec 19, 9:05 am, "io_x" <a...@b.c.invalid> wrote:
"James Kanze" <james.ka...@gmail.com> ha scritto nel messaggionews:d3cde4c3-dd7d-473b-b71d-b82fcef30e26@o28g2000yqh.googlegroups.com...
Somehow, I don't think you've understood what is going on.
yes i'm not so smart, but how to use all this?
It's not a question of "smart", it's a question of what you've
learned (or haven't learned). It this case, given your comments
and your code, I suspect that there's a lot of basic C++ and OO
to which you haven't been exposed. Enough that it can't be
addressed in a simple answer here---a good book is in order. (I
would suggest Stroustrup's most recent book for starters. It's
one of the best tutorial texts for "programming" that I've seen
to date: it doesn't teach C++ as such, it teaches programming,
using C++ as a major tool.)
Until you've actually learned about inheritance, abstract base
classes, and how and why they are used, you won't be able to
make sense out of my code.
why declare all distructors "virtual" ?
Because once I've constructed an object, I will only use it
through a pointer to the base class. And deleting an object
through a pointer to the base class is only legal if the
destructor is virtual.
why use all that "const"?
Because I felt like it:-).
Seriously, as designed, I expect all of the derived classes to
be immutable, so const correctness says that all of my functions
should be const, and that all of my pointers be const. In some
cases, const correctness is important, but not when all objects
must be allocated on the heap; I could just as easily dropped
all of the const, with no significant difference. What doesn't
work is mixing the two approaches: either everything const
correct, or nothing.
--
James Kanze