Re: Ambiguous in MI

James Kanze <>
Mon, 2 Nov 2009 01:33:18 -0800 (PST)
On Oct 31, 5:36 pm, Pavel
<> wrote:

James Kanze wrote:


I suspect (but I'm really just guessing) that what he's
expecting is the behavior of Java: that C::fun() will
provide the implementation of B::fun(), just because the
function happens to accidentally have the same name in two
different, unrelated classes. C++ doesn't have this defect
in the language; you have to explicitly tell the compiler
that the implementation in C::fun() is the one you want
here, by defining an A::fun() which calls C::fun().

You are confusing me.. Care to share an example of Java code
you had in mind?

It's been a while since I've last programmed in Java, but if I
recall correctly, something like the following is perfectly good

    interface I
        void f();

    class B
        public void f() {}

    class D extends B implements I

The B::f() overides the I::f(), even though the author of B has
no idea what I is or expects. Given the equivalent in C++:

    class I
        virtual ~I() {}
        virtual void f() = 0;

    class B
        void f() {}

    class D : public B, public I

, class D is still abstract, since the function B::f() does not
override I::f(). The author of D must make it explicit by
defining D::f().

James Kanze

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