C++：钻石问题

【问题标题】：C++: Diamond concernsC++：钻石问题
【发布时间】：2012-01-11 17:54:47
【问题描述】：

简单的问题：这种层次结构会导致 DP 吗？

//Abstract base class
class A {
    //Implement pure virtual methods with a default definition.
    //Pure virtual methods are still declared pure virtual.
};

//Abstract derived class
class B : public A {
    //Define pure virtual methods with a default definition.
    //Pure virtual methods are still declared pure virtual.
};

//Abstract base class
class C {
    //Define pure virtual methods with a default definition.
    //Pure virtual methods are still declared pure virtual.
};

//Concrete class
class D : public B, public C {
    //Implement all methods from D, B, and C
};

【问题讨论】：

标签： c++ diamond-problem

【解决方案1】：

没有。画图；所有的碱基都是独一无二的：

A
|
V
B   C
 \ /
  V
  D

“钻石问题”仅适用于由于多个重复基类而导致的不明确基类，例如如果D 是从A -> B 和A -> C 派生的：

No-diamond-problematic:                 Virtually-inherited diamond:

        A   A                                         A
        |   |                                       v/ \v
        B   C                                       B   C
         \ /                                         \ /
          V                                           V
          D                                           D

【讨论】：