{"id":1587,"date":"2024-11-27T23:56:32","date_gmt":"2024-11-27T15:56:32","guid":{"rendered":"https:\/\/www.fanyamin.com\/wordpress\/?p=1587"},"modified":"2024-11-27T23:56:32","modified_gmt":"2024-11-27T15:56:32","slug":"%e5%a5%87%e5%bc%82%e6%a8%a1%e6%9d%bf%e6%a8%a1%e5%bc%8f%ef%bc%88curiously-recurring-template-pattern%ef%bc%89","status":"publish","type":"post","link":"https:\/\/www.fanyamin.com\/wordpress\/?p=1587","title":{"rendered":"\u5947\u5f02\u6a21\u677f\u6a21\u5f0f\uff08Curiously Recurring Template Pattern\uff09"},"content":{"rendered":"

\u5728 C++ \u4e2d\uff0c\u201c\u5947\u5f02\u6a21\u677f\u201d\uff08Curiously Recurring Template Pattern, \u7b80\u79f0 CRTP\uff09\u662f\u4e00\u79cd\u5e38\u7528\u7684\u6a21\u677f\u7f16\u7a0b\u6280\u5de7\uff0c\u4e3b\u8981\u7528\u4e8e\u5b9e\u73b0\u9759\u6001\u591a\u6001\uff08static polymorphism\uff09\u6216\u4e3a\u6d3e\u751f\u7c7b\u63d0\u4f9b\u901a\u7528\u7684\u529f\u80fd\u3002\u5b83\u7684\u540d\u5b57\u6765\u6e90\u4e8e\u5176\u9012\u5f52\u7684\u7ed3\u6784\uff1a\u4e00\u4e2a\u7c7b\u4f7f\u7528\u81ea\u5df1\u4f5c\u4e3a\u6a21\u677f\u53c2\u6570\u4f20\u9012\u7ed9\u57fa\u7c7b\u3002<\/p>\n

CRTP \u7684\u57fa\u672c\u7ed3\u6784<\/h2>\n

CRTP \u7684\u6838\u5fc3\u662f\u5b9a\u4e49\u4e00\u4e2a\u57fa\u7c7b\u6a21\u677f\uff0c\u5e76\u8ba9\u6d3e\u751f\u7c7b\u4f5c\u4e3a\u6a21\u677f\u53c2\u6570\u4f20\u9012\u7ed9\u8fd9\u4e2a\u57fa\u7c7b\u3002<\/p>\n

\u57fa\u672c\u4ee3\u7801\u793a\u4f8b<\/p>\n

#include <iostream>\n\n\/\/ \u57fa\u7c7b\u6a21\u677f\ntemplate <typename Derived>\nclass Base {\npublic:\n    void interface() {\n        \/\/ \u8c03\u7528\u6d3e\u751f\u7c7b\u7684\u65b9\u6cd5\n        static_cast<Derived*>(this)->implementation();\n    }\n\n    \/\/ \u9ed8\u8ba4\u5b9e\u73b0\uff08\u53ef\u9009\uff09\n    void implementation() {\n        std::cout << "Base implementation\\n";\n    }\n};\n\n\/\/ \u6d3e\u751f\u7c7b\nclass Derived : public Base<Derived> {\npublic:\n    void implementation() {\n        std::cout << "Derived implementation\\n";\n    }\n};\n\nint main() {\n    Derived d;\n    d.interface();  \/\/ \u8f93\u51fa "Derived implementation"\n    return 0;\n}<\/code><\/pre>\n
\u5173\u952e\u70b9<\/p>\n
1.  \u6a21\u677f\u53c2\u6570\u4f20\u9012\u6d3e\u751f\u7c7b\uff1a\n\u2022   \u57fa\u7c7b\u6a21\u677f Base \u7684\u6a21\u677f\u53c2\u6570\u662f\u6d3e\u751f\u7c7b Derived\u3002\n\u2022   \u5728 Base \u4e2d\uff0c\u901a\u8fc7\u5c06 this \u6307\u9488\u9759\u6001\u8f6c\u6362\u4e3a Derived* \u7c7b\u578b\uff0c\u8c03\u7528\u6d3e\u751f\u7c7b\u4e2d\u7684\u65b9\u6cd5\u3002\n\n2.  \u9759\u6001\u591a\u6001\uff1a\n\u2022   \u5728\u7f16\u8bd1\u671f\u51b3\u5b9a\u8c03\u7528\u7684\u662f\u54ea\u4e00\u4e2a\u7c7b\u7684\u65b9\u6cd5\uff0c\u907f\u514d\u4e86\u8fd0\u884c\u65f6\u7684\u865a\u51fd\u6570\u5f00\u9500\u3002\n\u2022   \u4e0d\u540c\u4e8e\u52a8\u6001\u591a\u6001\uff08\u4f7f\u7528\u865a\u51fd\u6570\u548c vtable\uff09\uff0c\u9759\u6001\u591a\u6001\u5728\u7f16\u8bd1\u671f\u76f4\u63a5\u5c55\u5f00\uff0c\u6027\u80fd\u66f4\u9ad8\u3002\n\n3.  \u9012\u5f52\u7684\u5947\u5f02\u6027\uff1a\n\u2022   \u6d3e\u751f\u7c7b\u5f15\u7528\u57fa\u7c7b\u6a21\u677f\uff0c\u5e76\u5c06\u81ea\u8eab\u4f5c\u4e3a\u6a21\u677f\u53c2\u6570\u4f20\u9012\uff0c\u56e0\u6b64\u79f0\u4e3a\u201c\u5947\u5f02\u201d\u3002<\/code><\/pre>\n
\u4f7f\u7528\u573a\u666f<\/h2>\n
1. \u5b9e\u73b0\u9759\u6001\u591a\u6001<\/h3>\n
CRTP \u901a\u5e38\u7528\u4e8e\u66ff\u4ee3\u865a\u51fd\u6570\u7684\u8fd0\u884c\u65f6\u591a\u6001\uff0c\u5c24\u5176\u662f\u6027\u80fd\u654f\u611f\u7684\u573a\u666f\u3002<\/p>\n
\u4ee3\u7801\u793a\u4f8b<\/p>\n
#include <iostream>\n\ntemplate <typename Derived>\nclass Shape {\npublic:\n    void draw() {\n        static_cast<Derived*>(this)->draw_impl();\n    }\n};\n\nclass Circle : public Shape<Circle> {\npublic:\n    void draw_impl() {\n        std::cout << "Drawing Circle\\n";\n    }\n};\n\nclass Square : public Shape<Square> {\npublic:\n    void draw_impl() {\n        std::cout << "Drawing Square\\n";\n    }\n};\n\nint main() {\n    Circle c;\n    Square s;\n    c.draw(); \/\/ \u8f93\u51fa "Drawing Circle"\n    s.draw(); \/\/ \u8f93\u51fa "Drawing Square"\n    return 0;\n}<\/code><\/pre>\n
2. \u4ee3\u7801\u590d\u7528<\/h3>\n
CRTP \u53ef\u4ee5\u7528\u4e8e\u57fa\u7c7b\u63d0\u4f9b\u4e00\u90e8\u5206\u901a\u7528\u529f\u80fd\uff0c\u800c\u6d3e\u751f\u7c7b\u4e13\u6ce8\u4e8e\u5b9e\u73b0\u7279\u5b9a\u903b\u8f91\u3002<\/p>\n
\u793a\u4f8b\uff1a\u7edf\u8ba1\u6d3e\u751f\u7c7b\u7684\u5b9e\u4f8b\u6570\u91cf<\/p>\n
#include <iostream>\n\ntemplate <typename Derived>\nclass Counter {\nprivate:\n    static int count;\npublic:\n    Counter() { ++count; }\n    ~Counter() { --count; }\n\n    static int getCount() { return count; }\n};\n\n\/\/ \u9759\u6001\u6210\u5458\u53d8\u91cf\u5b9a\u4e49\ntemplate <typename Derived>\nint Counter<Derived>::count = 0;\n\nclass MyClass : public Counter<MyClass> {};\nclass AnotherClass : public Counter<AnotherClass> {};\n\nint main() {\n    MyClass a, b;\n    AnotherClass c;\n\n    std::cout << "MyClass instances: " << MyClass::getCount() << "\\n"; \/\/ \u8f93\u51fa 2\n    std::cout << "AnotherClass instances: " << AnotherClass::getCount() << "\\n"; \/\/ \u8f93\u51fa 1\n\n    return 0;\n}<\/code><\/pre>\n
3. \u63a7\u5236\u6d3e\u751f\u7c7b\u7684\u884c\u4e3a<\/h3>\n
\u57fa\u7c7b\u6a21\u677f\u53ef\u4ee5\u5bf9\u6d3e\u751f\u7c7b\u65bd\u52a0\u4e00\u5b9a\u7684\u7ea6\u675f\u6216\u7edf\u4e00\u63a5\u53e3\u3002<\/p>\n
\u4f18\u7f3a\u70b9<\/p>\n
\u4f18\u70b9<\/p>\n
1.  \u9759\u6001\u591a\u6001\uff1a\n\u2022   \u63d0\u9ad8\u6027\u80fd\uff0c\u65e0\u9700\u865a\u51fd\u6570\u548c\u8fd0\u884c\u65f6\u591a\u6001\u7684\u5f00\u9500\u3002\n\n2.  \u4ee3\u7801\u590d\u7528\uff1a\n\u2022   \u57fa\u7c7b\u6a21\u677f\u53ef\u4ee5\u5c01\u88c5\u901a\u7528\u903b\u8f91\uff0c\u6d3e\u751f\u7c7b\u53ea\u9700\u4e13\u6ce8\u4e8e\u5177\u4f53\u5b9e\u73b0\u3002\n\n3.  \u7075\u6d3b\u6027\uff1a\n\u2022   \u5728\u57fa\u7c7b\u6a21\u677f\u4e2d\u53ef\u4ee5\u4e3a\u6d3e\u751f\u7c7b\u63d0\u4f9b\u9ed8\u8ba4\u5b9e\u73b0\uff0c\u4e5f\u53ef\u4ee5\u5f3a\u5236\u6d3e\u751f\u7c7b\u5b9e\u73b0\u7279\u5b9a\u884c\u4e3a\u3002<\/code><\/pre>\n
\u7f3a\u70b9<\/p>\n
1.  \u53ef\u8bfb\u6027\u964d\u4f4e\uff1a\n\u2022   \u5bf9\u65b0\u624b\u6765\u8bf4\uff0c\u9012\u5f52\u7684\u6a21\u677f\u7ed3\u6784\u53ef\u80fd\u4e0d\u5bb9\u6613\u7406\u89e3\u3002\n\n2.  \u7c7b\u578b\u5b89\u5168\u6027\uff1a\n\u2022   \u5982\u679c\u4f7f\u7528\u4e0d\u5f53\uff08\u4f8b\u5982 static_cast \u9519\u8bef\uff09\uff0c\u53ef\u80fd\u5f15\u53d1\u672a\u5b9a\u4e49\u884c\u4e3a\u3002\n\n3.  \u7f16\u8bd1\u65f6\u95f4\u5f00\u9500\uff1a\n\u2022   \u6a21\u677f\u4f1a\u589e\u52a0\u7f16\u8bd1\u65f6\u95f4\uff0c\u56e0\u4e3a CRTP \u662f\u57fa\u4e8e\u6a21\u677f\u5143\u7f16\u7a0b\u7684\u3002<\/code><\/pre>\n
\u603b\u7ed3<\/h2>\n
CRTP \u662f C++ \u6a21\u677f\u7f16\u7a0b\u4e2d\u7684\u4e00\u4e2a\u5f3a\u5927\u5de5\u5177\uff0c\u4e3b\u8981\u7528\u4e8e\u9759\u6001\u591a\u6001\u548c\u4ee3\u7801\u590d\u7528\u3002\u5b83\u901a\u8fc7\u5c06\u6d3e\u751f\u7c7b\u4f5c\u4e3a\u6a21\u677f\u53c2\u6570\u4f20\u9012\u7ed9\u57fa\u7c7b\uff0c\u5b9e\u73b0\u4e86\u5728\u7f16\u8bd1\u671f\u786e\u5b9a\u7684\u591a\u6001\u884c\u4e3a\uff0c\u5728\u9ad8\u6027\u80fd\u573a\u666f\u4e2d\u5c24\u4e3a\u5e38\u89c1\u3002<\/p>\n","protected":false},"excerpt":{"rendered":"
\u5728 C++ \u4e2d\uff0c\u201c\u5947\u5f02\u6a21\u677f\u201d\uff08Curiously Recurring Template Pattern, \u7b80\u79f0 CRTP\uff09\u662f\u4e00\u79cd\u5e38\u7528\u7684\u6a21\u677f\u7f16\u7a0b\u6280\u5de7\uff0c\u4e3b\u8981\u7528\u4e8e\u5b9e\u73b0\u9759\u6001\u591a\u6001\uff08static polymorphism\uff09\u6216\u4e3a\u6d3e\u751f\u7c7b\u63d0\u4f9b\u901a\u7528\u7684\u529f\u80fd\u3002\u5b83\u7684\u540d\u5b57\u6765\u6e90\u4e8e\u5176\u9012\u5f52\u7684\u7ed3\u6784\uff1a\u4e00\u4e2a\u7c7b\u4f7f\u7528\u81ea\u5df1\u4f5c\u4e3a\u6a21\u677f\u53c2\u6570\u4f20\u9012\u7ed9\u57fa\u7c7b\u3002 CRTP \u7684\u57fa\u672c\u7ed3\u6784 CRTP \u7684\u6838\u5fc3\u662f\u5b9a\u4e49\u4e00\u4e2a\u57fa\u7c7b\u6a21\u677f\uff0c\u5e76\u8ba9\u6d3e\u751f\u7c7b\u4f5c\u4e3a\u6a21\u677f\u53c2\u6570\u4f20\u9012\u7ed9\u8fd9\u4e2a\u57fa\u7c7b\u3002 \u57fa\u672c\u4ee3\u7801\u793a\u4f8b #include <iostream> \/\/ \u57fa\u7c7b\u6a21\u677f template <typename Derived> class Base { public: void interface() { \/\/ \u8c03\u7528\u6d3e\u751f\u7c7b\u7684\u65b9\u6cd5 static_cast<Derived*>(this)->implementation(); } \/\/ \u9ed8\u8ba4\u5b9e\u73b0\uff08\u53ef\u9009\uff09 void implementation() { std::cout << "Base implementation\\n"; } }; \/\/ \u6d3e\u751f\u7c7b class Derived : public Base<Derived> { public: void implementation() { […] →Read more<\/a><\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[5],"tags":[],"class_list":["post-1587","post","type-post","status-publish","format-standard","hentry","category-5"],"_links":{"self":[{"href":"https:\/\/www.fanyamin.com\/wordpress\/index.php?rest_route=\/wp\/v2\/posts\/1587"}],"collection":[{"href":"https:\/\/www.fanyamin.com\/wordpress\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.fanyamin.com\/wordpress\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.fanyamin.com\/wordpress\/index.php?rest_route=\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/www.fanyamin.com\/wordpress\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=1587"}],"version-history":[{"count":1,"href":"https:\/\/www.fanyamin.com\/wordpress\/index.php?rest_route=\/wp\/v2\/posts\/1587\/revisions"}],"predecessor-version":[{"id":1588,"href":"https:\/\/www.fanyamin.com\/wordpress\/index.php?rest_route=\/wp\/v2\/posts\/1587\/revisions\/1588"}],"wp:attachment":[{"href":"https:\/\/www.fanyamin.com\/wordpress\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=1587"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.fanyamin.com\/wordpress\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=1587"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.fanyamin.com\/wordpress\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=1587"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}