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;
} |