link-contructed
Ca-contructed
Cb-contructed
Ca-run
Cb-run
Ca-destructed
Cb-destructed
link-destructed

/*
vim: ts=4 :
g++ -lstdc++ -o linked linked.cpp && ./linked
*/

#include <iostream>
using namespace std;

class Ctask {
public:
    Ctask *next = NULL;
    Ctask(void) {}
    virtual ~Ctask(void) {}
    virtual void run(void) = 0;
};

/* --------------------------------- */

class Clink {
public:
    Clink(void) {
        cout << "link-contructed" << endl;
    }
    ~Clink(void) {
        Ctask *temp;
        while (temp = head) {
            head = head->next;
            delete temp;
        }
        cout << "link-destructed" << endl;
    }
    void run(void) {
        Ctask *temp = head;
        while (temp) {
            temp->run();
            temp = temp->next;
        }
    }
    void add(Ctask *newnode) {
        if (tail)
            tail->next = newnode;
        else
            head = newnode;
        tail = newnode;
    }
private:
    Ctask *head = NULL;
    Ctask *tail = NULL;
};

/* --------------------------------- */

class Ca: public Ctask {
public:
    Ca(void) {
        cout << "Ca-contructed" << endl;
    }
    ~Ca(void) {
        cout << "Ca-destructed" << endl;
    }
    void run(void) {
        cout << "Ca-run" << endl;
    }
};

class Cb: public Ctask {
public:
    Cb(void) {
        cout << "Cb-contructed" << endl;
    }
    ~Cb(void) {
        cout << "Cb-destructed" << endl;
    }
    void run(void) {
        cout << "Cb-run" << endl;
    }
};

/* --------------------------------- */

int main(void) {
    Clink link;
    link.add((Ctask *)new Ca());
    link.add((Ctask *)new Cb());
    link.run();
    return 0;
}