c++常用设计模式实现

单例模式：

namespace downgadget{class Downloader_c {public:static Downloader_c* Instance(){static Downloader_c* s_downloader = new Downloader_c();return s_downloader;}private:Downloader_c(){}                   // ConstructorDownloader_c(Downloader_c const&);    // Don't Implementvoid operator=(Downloader_c const&); // Don't implementprivate:};}