Re: overriding some of the methods with the same name yields an error
Oren wrote:
Hi
There is a question I'm trying to solve for some time without any
success:
When a base class has several methods with the same name (overloaded)
and a derived class overrides one or some of the methods all other (not
overridden) methods are hidden as well.
for example:
#include <iostream>
using namespace std;
class B
{
public:
virtual void foo(const char* arg)
{cout<<"B::foo(const char*):"<<arg<<endl;}
virtual void foo(int arg)
{cout<<"B::foo(int):"<<arg<<endl;}
};
class D :public B
{
public:
virtual void foo(int arg)
{cout<<"D::foo(int):"<<arg<<endl;}
};
int main()
{
D* d = new D();
d->foo("hello");
d->foo(3);
delete d;
return 0;
}
this example refuses to compile on account of the "hello" char[6] not
able to be converted to an int. I tried it on g++ and VC6 and both did
the same so I guess it's not a compiler bug but rather a standard rule
or direction.
Indeed; add "using B::foo;" to D's definition if you
want to bring in the name from the base class.
BTW when d's type is replaced to a B* the program runs OK.
my question is why am I seeing this behavior and what is the logic
behind this?
Name lookup is separate from overload resolution (and
precedes it). This keeps the rules simple and consistent,
though it's not the only possible solution. I believe it
may also have been through a desire to stop changes in
(possibly non-virtual) base class functions affecting
users of derived classes (though I'm not sure I agree
with that philosophy).
-- James
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