boost::factory 创建 boost::enable_shared_from_this 类

Question

我有多个从 A 派生的类

class A : public boost::enable_shared_from_this<A> {
    public:
        typedef boost::shared_ptr<A>    pointer;

        static pointer create(tcp::socket& socket) {
            return pointer(new A(socket));
        }
    private:
        A(&tcp::socket socket) : m_socket(socket) {}

        tcp::socket&    m_socket;
}

Class Aa : public A {
    public:
        typedef boost::shared_ptr<Aa>   pointer;

        static pointer create(tcp::socket& socket) {
            return pointer(new Aa(socket));
        }

    private:
        Aa(&tcp::socket socket) : A(socket) {}
}

Class Ab : public A {
    public:
        typedef boost::shared_ptr<Ab>   pointer;

        static pointer create(tcp::socket& socket) {
            return pointer(new Ab(socket));
        }

    private:
        Ab(&tcp::socket socket) : A(socket) {}
}

[...]

Class Ax : public A {
    public:
        typedef boost::shared_ptr<Ax>   pointer;

        static pointer create(tcp::socket& socket) {
            return pointer(new Ax(socket));
        }

    private:
        Ax(&tcp::socket socket) : A(socket) {}
}

我想使用 boost::factory 创建一个工厂模式 我写过类似的东西：

class MyFactory {
    public:
        static MyFactory* getInstance();

        typedef boost::function< A(tcp::socket) > a_fact;

    private:
        MyFactory() {
            map["Aa"] = boost::bind(boost::factory< Aa::create >, _1);
            map["Ab"] = boost::bind(boost::factory< Ab::create >, _1);
            […]
            map["Ax"] = boost::bind(boost::factory< Ax::create >, _1);
        }

        std::map<std::string, a_fact>   map;
    };

当然，它不会编译...... 给我错误：

MyFactory.cc:13: error: type/value mismatch at argument 1 in template parameter list for ‘template<class Pointer, class Allocator, boost::factory_alloc_propagation AP> class boost::factory’
MyFactory.cc:13: error:   expected a type, got ‘Aa::create’

任何想法，我应该如何实现它？

Answer 1

在文档中，参数传递给factory-template 是您期望结果的指针类型。因此，在您的情况下 boost::factory。

Answer 2

如果有人犯同样的错误，这里有答案。
它不需要boost::factory来工作，直接使用boost::function就足够了。

所以

class MyFactory {
    public:
        static MyFactory* getInstance();

        typedef boost::function< A(tcp::socket) > a_fact;

    private:
        MyFactory() {
            map["Aa"] = boost::bind(&Aa::create, _1);
            map["Ab"] = boost::bind(&Ab::create, _1);
            […]
            map["Ax"] = boost::bind(&Ax::create, _1);
        }

        std::map<std::string, a_fact>   map;
    };

效果很好！！！