🚀 go-pugleaf

On Thu, 20 Jun 2002 13:01:31 -0400, Tris Orendorff wrote:

>> What's the problem with the above? In true multiple inheritance, where
>> you're inheriting multiple _implementations_, the diamond-of-death
>> occurs where you're not sure which _inherited_ implementation to invoke
>> first, or whether it's desirable to invoke one first. With Java, you
>> have multiple inheritance on at the _interface_ level, which alleviates
>> the diamond-of-death problem: you only have one inherited
>> implementation on
> 
> I'm sorry.  What exactly is the "the diamond-of-death?"

In C++, you can have the following:

class Base
{
public:
    virtual void doFoo();
};

class Child1:public Base
{
public:
    void doFoo(); 
};

class Child2:public Base
{
public:
    void doFoo();
};

class Grandchild1:public Child1,Child2
{
public:
    void doFoo();
};

Child1 and Child2 inherited Base and override the dooFoo() method.
Grandchild1 inherits _both_ Child1 and Child2, and overrides doFoo().
Now, when Granchild1::doFoo() invokes the methods inherited, _which_ one
does it invoke first? That is the diamond-of-death, and is avoided by
Java's not allowing multiple inheritance of _implementations_. You no
longer have to decide which implementation you're inheriting to invoke
first, since you can only inherit _one_. 

HTH. =)

-- 
Darryl L. Pierce <mcpierce@databasix.com>
Visit the Infobahn Offramp <http://welcome.to/mcpierce>
"What do you care what other people think, Mr. Feynman?"