c++纯虚函数在父类中调用的规避

构造和析构函数不允许调用纯虚函数，可以先调用虚函数，里面再调用纯虚函数实现。

class Base{
public:
    virtual void foo()=0;
    Base() { call_foo();}
    void call_foo() { foo(); }
};
 
class Derived: Base{
    void foo() {  }
};
 
int main() {
    Derived d;
}

 

在父类中定义纯虚函数，实现工厂生产。子类再实现。可以用虚函数里面调用纯虚函数实现。

父类实现了线程，子类实现方法即可示例：

 

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//============================================================================ // Name        : mytestcpp.cpp // Author      : // Version     : // Copyright   : Your copyright notice // Description : Hello World in C++, Ansi-style //============================================================================   #include <iostream>   using namespace std;   #include <string> #include <iostream> #include "pthread.h" using namespace std;   class ITestComponent { public:       virtual void* thread_run(void* para)=0;       virtual void* thread_run_tmp(void* para) {         thread_run(para);     }     ;     virtual void start() {         typedef void* (*FUNC)(void*); //定义FUNC类型是一个指向函数的指针，该函数参数为void*，返回值为void*         FUNC callback = (FUNC) &ITestComponent::thread_run_tmp; //强制转换func()的类型           int rc;         pthread_t thread_instance;         pthread_attr_t attr; // Thread attribute           pthread_attr_init(&attr);         pthread_attr_setscope(&attr, PTHREAD_SCOPE_SYSTEM);         pthread_attr_setdetachstate(&attr, PTHREAD_CREATE_DETACHED);           rc = pthread_create(&thread_instance, &attr, callback, this);         if (rc) {             cout << "thread_instance thread ERROR; return code is  " << rc << endl;         }         pthread_attr_destroy(&attr);       }   protected: };   class HardwareMeter: public ITestComponent { public:     void* thread_run(void *para) {         while (1) {             cout << "HardwareMeter " << " start." << endl;         }       } };   int main() {     cout << "!!!Hello World!!!" << endl; // prints !!!Hello World!!!     HardwareMeter hm;     hm.start();     cin >> i;     return 0; }