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：

//============================================================================
// 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;
}