在模板化类中初始化static std :: map成员？

Question

这是我项目的代码片段:

template<typename Second, typename First = const UINT64>
class Event : virtual public id_manager<>
{
    friend class EventHandler;
    typedef std::map<First, EventHandler> eventMap;
    static eventMap mapper;
    static eventMap StartMapping()
    {
        eventMap temp;
        return temp;
    }
public:
    Event(){}
    void operator+=(EventHandler _handler)
    {
        mapper[this->getID()] = _handler;
    }
};
// INITIALIZATION FAILED HERE:
template<typename Second, typename First = const UINT64>
Event<Second, First>::eventMap Event<Second, First>::mapper(Event<Second, First>::StartMapping());

这是Visual Studio 2010的输出错误:

警告1警告C4346:'Event :: eventMap':依赖名称不是类型c:\ users\admin\documents\visual studio 2010\projects\cppsystem\cppsystem\main.cpp 67错误2错误C2143:语法错误:缺失';' 在'Event :: mapper'c:\ users\admin\documents\visual studio 2010\projects\cppsystem\cppsystem\main.cpp之前67错误3错误C4430:缺少类型说明符 - 假定为int.注意:C++不支持default-int c:\ users\admin\documents\visual studio 2010\projects\cppsystem\cppsystem\main.cpp 67错误4错误C1903:无法从先前的错误中恢复; 停止编译c:\ users\admin\documents\visual studio 2010\projects\cppsystem\cppsystem\main.cpp 67

我希望这段代码足够了.我无法使用该地图的"初始化功能"初始化静态地图成员.非常感谢!

Answer 1

您需要typename告诉编译器eventMap是一个类型.

template<typename Second, typename First = const UINT64>
typename Event<Second, First>::eventMap Event<Second, First>::mapper(Event<Second, First>::StartMapping());

请参阅"typename"关键字