c++ - 以不同产品的返回值(value) boost 工厂

Question

我使用boost factory来创建产品，我想做的是为它的DoSomething()调用不同的产品，但问题是我希望每个产品的返回值都不同，并且它们都是结构。我要ProductA->DoSomething()，那么它的返回值就是structA，对于ProductB->DoSomething()，它的返回值就是strucB。并且所有结构都从基础 struct 驱动，这可能吗？感谢您的解决方案，非常感谢!

Answer 1

您可以声明基础 struct ReturnType ，它将定义基础方法和变量。然后您就可以毫无问题地创建产品。

struct ReturnType
{
    virtual std::string getName(){}
};
struct MarsType : ReturnType 
{
    std::string specialMethod()
    {
        return "MARS";
    }
};
struct SnikersType : ReturnType 
{
    std::string specialMethod2()
    {
        return "SNIKERS";
    }
};

class Product
{
    public:
        virtual ReturnType* doSomething()=0;
};

class SnikersProduct : public Product
{
public:
    ReturnType* doSomething()
    {
        return static_cast<ReturnType*>(&value);
    }
private:
    SnikersType value;
};

class MarsProduct : public Product
{
public:
    ReturnType* doSomething()
    {
        return static_cast<ReturnType*>(&value);
    }
private:
    MarsType value;
};

class Creator
{
public:
    virtual Product* createProduct()=0;
};


class SnikersCreator : public Creator
{
public:
    Product* createProduct()
    {
        return new SnikersProduct();
    }
};

class MarsCreator : public Creator
{
public:
    Product* createProduct()
    {
        return new MarsProduct();
    }
};

int main()
{
    std::vector<Creator*> creators;
    creators.push_back(new MarsCreator());
    creators.push_back(new SnikersCreator());
    Product* mars = creators[0]->createProduct();
    Product* snikers = creators[1]->createProduct();
    std::cout<<"mars product returns "<<dynamic_cast<MarsType*>(mars->doSomething())->specialMethod()<<std::endl;
    std::cout<<"snikers product returns "<<dynamic_cast<SnikersType*>(mars->doSomething())->specialMethod2()<<std::endl;
    return 0;
}

输出是:

mars product returns MARS
snikers product returns SNIKERS