Question

我正在学习一些设计模式。我坚持使用继承的Singleton，这是我的代码：

#ifndef FACTORY_CPP
#define FACTORY_CPP
#include "Istogramma.cpp"
class Factory
{

protected:
 Factory(){}
 static Factory * istance;

public:
 static Factory* getIstance(){

    return istance;
 }
 virtual Istogramma* creaIstogramma()=0;
};

#endif

这是我的单身基类。现在是子类：

class FactoryConAB : public Factory
{
protected:
 FactoryConAB(){}
public:
 static void Istance()
 {
    if(istance == 0){
        istance = new FactoryConAB;
    }
 }
 virtual Istogramma* creaIstogramma(){
    return new IstogrammaConAB;
 }

  }; 
#endif

现在主要：

#include <iostream>
#include "applicazione.cpp"
#include "FactoryConCancelletto.cpp"
#include "FactoryConAB.cpp"
using namespace std;

int main ()
{
    FactoryConAB::Istance();
    Applicazione singleton;
    singleton.disegna(30);
    return 0 ;
}

当我编译时，我收到此错误：

g++  -o "SingletonFactory"  ./Factory.o ./FactoryConAB.o ./FactoryConCancelletto.o ./Istogramma.o ./IstogrammaConAB.o ./IstogrammaConCancelletto.o ./applicazione.o ./main.o   
./main.o: In function `FactoryConAB::Istance()':
/home/haze/workspace/SingletonFactory/Debug/../FactoryConAB.cpp:14: undefined reference to `Factory::istance'
makefile:44: recipe for target 'SingletonFactory' failed
/home/haze/workspace/SingletonFactory/Debug/../FactoryConAB.cpp:15: undefined reference to `Factory::istance'
collect2: error: ld returned 1 exit status
make: *** [SingletonFactory] Error 1

有人可以解释为什么我会收到这个错误吗？如果有人链接到模式并希望分享我真的很感激！

C ++使用继承的Singleton类

0 个答案: