classFactory自动添加到ClasStypeFactory中
ClassFactory automatic added to ClassTypeFactory
我有三个类。一个看起来像这样的ClassFactoryBase
:
class ClassFactoryBase {
public:
virtual ~ClassFactoryBase () = default;
virtual AbstractBase* Create() = 0;
};
我从该类继承了实际工厂作为模板
template <typename Type>
class ClassFactory final : public ClassFactoryBase {
ClassFactory (/*ClassFactoryBase& Factory*/); //Idea to automatically add them
~ClassFactory () = default;
AbstractBase* Create() override; //returns new Type
};
和OFC我实施了工厂本身:
class ClassTypeFactory {
public:
template<typename Type>
void AddFactory(ClassFactoryBase& ClassFactory); // inserts ClassFactory into the map m_Factories
AbstractBase* Create(const std::string& ClassType);
private:
std::map<std::string, ClassFactoryBase&> m_Factories;
};
如果我这样实现了,我必须在main.cpp
的内部添加到它。ClassTypeFactory class_type_factory;
ClassFactory<TopClass> top_state_factory(&class_type_factory);
class_type_factory.AddFactory<TopClass>(top_class_factory); // leave this out
这很好,但是我想知道我是否可以以一种可以忽略最后一行的方式实现它。我认为它应该起作用,因为它们都使用相同的模板参数。我试图给我的classFactory对工厂的引用,而不是在其中调用AddFactory
方法,但我无法使其起作用。我总是会遇到无法访问的错误。
您只需要按正确的顺序进行操作即可。遵循示例的修改版本(使用智能指针(:
// Your objects to create:
struct AbstractBase
{
virtual ~AbstractBase () = default;
// ...
};
struct Derived : AbstractBase
{
// ...
};
// Your abstract factory
class ClassFactoryBase {
public:
virtual ~ClassFactoryBase () = default;
virtual std::unique_ptr<AbstractBase> Create() = 0;
};
// Your factory collection
class ClassTypeFactory {
public:
void AddFactory(const std::string& name, ClassFactoryBase& factory) { m_Factories.emplace(name, std::ref(factory)); }
std::unique_ptr<AbstractBase> Create(const std::string& name)
{
return m_Factories.at(name).get().Create();
}
private:
std::map<std::string, std::reference_wrapper<ClassFactoryBase>> m_Factories;
};
// Your real factory
template <typename Type>
class ClassFactory final : public ClassFactoryBase {
public:
ClassFactory(const std::string& name, ClassTypeFactory& factory) { factory.AddFactory(name, *this); }
std::unique_ptr<AbstractBase> Create() override { return std::make_unique<Type>(); }
};
然后用法:
ClassTypeFactory class_type_factory;
ClassFactory<Derived> top_state_factory("TopClass", class_type_factory);
auto ptr = class_type_factory.Create("TopClass");
demo
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