异质链表

 程序中，用基类类型指针，可以生成一个连接不同派生类对象的动态链表，

即每个节点指针可以指向类层次中不同的派生类对象。

这种节点类型不相同的链表称为异质链表。

如：任务管理器，管理不同的进程

#include "dialog.h"
#include <QApplication>
#include <QLabel>
#include <QPushButton>

class Base
{
public:
    virtual void show() = 0;
    virtual ~Base(){}
};

class Node
{
public:
    Node *next;
    Base *data;
};

class YiZhiLinkList
{
public:
    YiZhiLinkList()
    {
        head = nullptr;
    }
    ~YiZhiLinkList()
    {
        if(head != nullptr) {
            delete head->data;
            head = head->next;
        }
    }

    Node* add(Base *base)
    {
        if (head == nullptr){
            head = new Node();
            head->data = base;
            head->next = nullptr;
        }
        else {
            Node *tmp = head;
            Node *n = new Node();
            n->data = base;
            n->next = nullptr;

            while(tmp->next != nullptr) {
                tmp = tmp->next;
            }

            tmp->next = n;

        }
        return head;
    }
    void show()
    {
        while (head != nullptr) {
            head->data->show();
            head = head->next;
        }
    }

private:
    Node *head;

};

class MyLable:public Base
{
private:
    QLabel label;
public:
    MyLable(){

    }
    ~MyLable(){

    }
    void show()
    {
        label.setText("This is label");
        label.show();
    }
};

class MyButton:public Base
{
private:
    QPushButton button;
public:
    MyButton(){

    }
    ~MyButton(){

    }
    void show()
    {
        button.setText("This is button");
        button.show();
    }
};

class MyDialog:public Base
{
private:
    Dialog w;
public:
    MyDialog(){

    }
    ~MyDialog(){

    }
    void show()
    {
        w.show();
    }
};

int main(int argc, char *argv[])
{
    QApplication a(argc, argv);

    Base *l = new MyLable();
    Base *b = new MyButton();
    Base *d = new MyDialog();

    YiZhiLinkList Yi;
    Yi.add(l);
    Yi.add(b);
    Yi.add(d);

    Yi.show();

    return a.exec();
}