Re: design problem with inheritance
On 8/23/2011 12:53 PM, alessio211734 wrote:
ok thanks for correction, I put a incomplete code but my problem is
another, how with this design I can access to private data of class
Duck
when implements the Fly method?
First off, what correction? If you post a reply, consider quoting or at
least commenting on what you're referring to.
Second, nobody but Duck (or its friends) can access private members of
Duck. If you need to get to those from derived classes, provide an
interface (possibly 'protected' to limit access to derived classes only)
in the Duck itself.
class NoFly: public FlyBehav{
public:
void Fly(){std::cout<<"Cannot Fly\n";}
};
class CanFly: public FlyBehav{
public:
void Fly()
{
// how get Duck private data???
std::cout<<"Flying across the sky\n";
}
};
if the Fly() method of CanFly or NoFly needs to privata data of the
class Duck how can do it with this design?
Maybe I could pass a pointer to base class Duck but so I can access
only to public member of Duck. I would like access to Duck private
data.
That's just a wrong premise. Private data are private for a very simple
reason: nobody should have access to them, not even derived classes. If
Duck needs to grant access to some data to the derived classes for
whatever reason, make the members 'protected'.
class FlyBehav{
public:
FlyBehav(Duck * _ownClass)
{
ownClass=_ownClass;
}
virtual void Fly()=0;
};
class CanFly: public FlyBehav{
public:
CanFly(Duck * ownClass)
{
}
void Fly()
{
std::cout<<"Flying across the sky\n";}
ownClass->DuckPublicMethod();
// no ways to acess to Duck private data or private
method!!!
}
};
V
--
I do not respond to top-posted replies, please don't ask