哪种情况下会使用C ++中的克隆以及如何使用它？ [英] Which situation will use clone in C++ and how to use it?

问题描述

虚拟克隆和克隆有什么区别？
我找到以下例子，它克隆派生到base，它是什么？

What is the difference between virtual clone and clone? I find the following example, it clone derived to base, what is it for?

class Base{
public:
    virtual Base* clone() {return new Base(*this);}
    int value;
    virtual void printme()
    {
        printf("love mandy %d\n", value);
    }
};
class Derived : public Base
{
public:
    Base* clone() {return new Derived(*this);}
    virtual void printme()
    {
        printf("derived love mandy %d\n", value);
    }
};

Derived der;
    der.value = 3;

    Base* bas = der.clone();
    bas->printme();

推荐答案

请考虑：

Base * b = get_a_base_object_somehow();

//现在，b可能是Base或Derived， / p>

// now, b might be of type Base, or Derived, or something else derived from Base

Base * c = b->clone();

//现在，c将与b的类型相同，它不知道它的类型。这是克隆方法有用的。

// Now, c will be of the same type as b was, and you were able to copy it without knowing its type. That's what clone methods are good for.

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