C++ function inheritance explained: When should inheritance not be used?

C function inheritance should not be used in the following situations: When a derived class requires a different implementation, a new function with a different implementation should be created. When a derived class does not require a function, it should be declared as an empty class or use private, unimplemented base class member functions to disable function inheritance. When functions do not require inheritance, other mechanisms (such as templates) should be used to achieve code reuse.

#C Detailed explanation of function inheritance: When should inheritance not be used?

Function inheritance is a powerful mechanism in C that allows derived classes to reuse functions in a base class. However, there are situations where using functional inheritance may not be appropriate. The following are several scenarios where function inheritance should not be used:

When the derived class requires a different implementation

If the derived class requires a different implementation of the function than the base class, then functional inheritance should not be used. In this case, it is more appropriate to create a new function with a different implementation.

Example:

class Shape {
public:
    virtual void draw() const = 0;
};

class Circle : public Shape {
public:
    void draw() const override {
        // 绘制圆形
    }
};

class Square : public Shape {
public:
    void draw() const override {
        // 绘制正方形
    }
};

In this example, the Circle and Square classes require different draw( ) Function implementation. Therefore, using functional inheritance is not appropriate.

When the derived class does not require functions

If the derived class does not require the use of base class functions, function inheritance should not be used. In this case, you can disable function inheritance by declaring the derived class as an empty class or by using a private, unimplemented base class member function.

Example:

class Shape {
public:
    virtual void draw() const = 0;
};

class Circle : public Shape {
public:
    using Shape::draw;  // 禁用函数继承
};

In this example, the Circle class does not require the draw() function. Therefore, use the using Shape::draw syntax to disable function inheritance.

When a function does not require inheritance

Function inheritance should not be used if the function is not the object of inheritance. For example, if a function is private or protected, it cannot be inherited by derived classes. In this case, code reuse can be achieved through other mechanisms such as templates.

Example:

class Shape {
private:
    void drawInternal() const;
};

class Circle : public Shape {
public:
    void draw() const {
        drawInternal();  // 无法访问私有成员函数
    }
};

In this example, the draw() function cannot be inherited by the Circle class because drawInternal() The function is private. Therefore, using functional inheritance is not appropriate.

In these cases, other alternatives such as composition, delegation, or templates should be considered to enable code reuse and code reuse.

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