什么,准确地区分私人和受保护(在Flex中)？

Question

在Flex(以及许多其他语言)中,类的函数/方法可以声明为私有或受保护(或公共).有什么不同？我的印象是它与子类的关系以及事物如何被继承或可以被调用有关,但我不确定究竟是什么.

Answer 1

一般来说:

• 私人成员只能由班级本身访问.
• 受保护的成员只能由类本身及其后代访问.
• 每个人都可以访问公共成员.

因此,当您从私人到受保护到公共时,可见性会增加.

在C++中,你可以控制会员的知名度应该与前面加上基类名被继承到后代private,protected或public关键字,这意味着你想要的基类成员的知名度,至多在这一水平.

class A {
private:
    int privA;
protected:
    int protA;
public:
    int pubA;

    // privA can be accessed inside class A
    // protA can be accessed inside class A
    // pubA  can be accessed inside class A
};
// pubA can be accessed by anyone

class B : public A {
    // No change to visibility of members
    // privA can't be accessed inside class B
    // protA can be accessed inside class B
    // pubA  can be accessed inside class B
};
// pubA can be accessed by anyone

class C : protected A {
    // Public members downgraded to protected
    // privA can't be accessed inside class C
    // protA can be accessed inside class C
    // pubA  can be accessed inside class C
};
// None of the members can be accessed outside class C

class D : private A {
    // Public and protected members downgraded to private
    // privA can't be accessed inside class D
    // protA can't be accessed inside class D
    // pubA  can't be accessed inside class D
};
// None of the members can be accessed outside class D

在上述每个案例中,后代课程当然能够介绍他们自己的私人,受保护和公共成员.