我参考这篇文章来实现一个类似于 TimW 的答案中描述的自注册类工厂,但它有一个很好的技巧,即使用模板化工厂代理类来处理对象注册。非常值得一看:)
C++ 中的自注册对象 -> http://www.ddj.com/184410633
编辑
这是我做的测试应用程序(整理了一下;):
对象工厂.h
#include <string>
#include <vector>
// Forward declare the base object class
class Object;
// Interface that the factory uses to communicate with the object proxies
class IObjectProxy {
public:
virtual Object* CreateObject() = 0;
virtual std::string GetObjectInfo() = 0;
};
// Object factory, retrieves object info from the global proxy objects
class ObjectFactory {
public:
static ObjectFactory& Instance() {
static ObjectFactory instance;
return instance;
}
// proxies add themselves to the factory here
void AddObject(IObjectProxy* object) {
objects_.push_back(object);
}
size_t NumberOfObjects() {
return objects_.size();
}
Object* CreateObject(size_t index) {
return objects_[index]->CreateObject();
}
std::string GetObjectInfo(size_t index) {
return objects_[index]->GetObjectInfo();
}
private:
std::vector<IObjectProxy*> objects_;
};
// This is the factory proxy template class
template<typename T>
class ObjectProxy : public IObjectProxy {
public:
ObjectProxy() {
ObjectFactory::Instance().AddObject(this);
}
Object* CreateObject() {
return new T;
}
virtual std::string GetObjectInfo() {
return T::TalkToMe();
};
};
对象.h
#include <iostream>
#include "object_factory.h"
// Base object class
class Object {
public:
virtual ~Object() {}
};
class ClassA : public Object {
public:
ClassA() { std::cout << "ClassA Constructor" << std::endl; }
~ClassA() { std::cout << "ClassA Destructor" << std::endl; }
static std::string TalkToMe() { return "This is ClassA"; }
};
class ClassB : public Object {
public:
ClassB() { std::cout << "ClassB Constructor" << std::endl; }
~ClassB() { std::cout << "ClassB Destructor" << std::endl; }
static std::string TalkToMe() { return "This is ClassB"; }
};
对象.cpp
#include "objects.h"
// Objects get registered here
ObjectProxy<ClassA> gClassAProxy;
ObjectProxy<ClassB> gClassBProxy;
主文件
#include "objects.h"
int main (int argc, char * const argv[]) {
ObjectFactory& factory = ObjectFactory::Instance();
for (int i = 0; i < factory.NumberOfObjects(); ++i) {
std::cout << factory.GetObjectInfo(i) << std::endl;
Object* object = factory.CreateObject(i);
delete object;
}
return 0;
}
输出:
This is ClassA
ClassA Constructor
ClassA Destructor
This is ClassB
ClassB Constructor
ClassB Destructor