C ++类和相互链接的对象形成一个循环 [英] C++ class and interlinked objects forming a cycle

问题描述

我如何实现互锁的对象结构，从而在C ++中形成一个循环

How could i achieve interlocked object structure that makes a cycle in C++

class Foo
{
    Bar bar;
};

class Bar
{
    Foo foo;
};

推荐答案

Foo.h

#include <memory>

class Bar; // Forward declare Bar class

class Foo
{
public:
    Foo();

private:
    std::unique_ptr<Bar> bar; // Use pointer so that header include is not necessary
};

Foo.cpp

#include "Foo.h"
#include "Bar.h" // Now include bar (in the cpp file to avoid circular includes)

Foo::Foo() :
    bar(new Bar())
{
    // Do nothing
}

对 Bar.h 和 Bar.cpp 使用相同的设置.

注意:上面的代码假定使用支持C ++ 11的编译器.但是，如果不是这种情况，则应使用原始指针(例如， Bar * bar )，并且必须强制使用 destructor 来调用 delete bar .为避免资源泄漏，这是必需的.当然，以上假设 Foo 和 Bar 拥有它们的成员指针是这些类的正确行为，但可以轻松更改，这不是正确的假设.

Note: The above code assumes a compiler supporting C++11 is used. However, if this is not the case then a raw pointer (e.g., Bar* bar) should be used and the destructor must be implented to call delete bar. This is necessary to avoid leaking the resource; of course the above assumes Foo and Bar owning their member pointer is the correct behavior for these classes but it can easily be changed this is not the correct assumption.

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