C++ 继承同名Impl简单测试构造顺序析构顺序

 
/*****class Base*****/

class Base
{
public:
    Base();
    virtual ~Base();
protected:
    struct Impl;
    Impl* m_Impl;
};

struct Base::Impl
{
    int num{ 100 };
};

Base::Base()
{
    m_Impl = new Impl;
    std::cout << "Base 构造!" << '\n';
}
Base::~Base()
{
    if (m_Impl)
    {
        delete m_Impl;
        m_Impl = nullptr;
        std::cout << "Base 析构!" << '\n';
    }
}

/********class A*********/

class A :public Base
{
public:
    A();
    ~A();
    void say();
protected:
    struct Impl;
    Impl* m_Impl;
};

struct A::Impl
{
    std::string name{ "A dog man!" };
};

A::A()
{
    m_Impl = new Impl;
    std::cout << "A 构造!" << '\n';
}
A::~A()
{
    delete m_Impl;
    std::cout << "A 析构!" << '\n';
}

void A::say()
{
    std::cout << "A say:" << '\n';
    std::cout << m_Impl->name << endl;
    std::cout << Base::m_Impl->num << endl;
    std::cout << '\n';
}

/********class B*********/

class B :public A
{
public:
    B();
    ~B();
    void say();
protected:
    struct Impl;
    Impl* m_Impl;
};

struct B::Impl
{
    std::string info{ "B is SB!" };
};

B::B()
{
    m_Impl = new Impl;
    std::cout << "B 构造!" << '\n';
}
B::~B()
{
    delete m_Impl;
    std::cout << "B 析构!" << '\n';
}

void B::say()
{
    std::cout << "B say:" << '\n';
    std::cout << m_Impl->info << endl;
    std::cout << A::m_Impl->name << endl;
    std::cout << Base::m_Impl->num << endl;
    std::cout << '\n';
}


int main()
{
    B* b = new B;

    std::cout << "-----分割-----" << '\n';
    b->say();

    std::cout << "-----分割-----" << '\n';
    b->A::say();
    delete b;

    system("pause");
    return EXIT_SUCCESS;
}

输出：

Base 构造!
A 构造!
B 构造!
-----分割-----
B say:
B is SB!
A dog man!
100

-----分割-----
A say:
A dog man!
100

B 析构!
A 析构!
Base 析构!