{"id":134,"date":"2018-09-14T01:21:33","date_gmt":"2018-09-13T17:21:33","guid":{"rendered":"https:\/\/syaro.hotococoa.moe\/wordpress\/?p=134"},"modified":"2018-09-14T11:38:19","modified_gmt":"2018-09-14T03:38:19","slug":"%e4%bb%8ec%e8%b0%88%e5%a4%9a%e6%80%81","status":"publish","type":"post","link":"https:\/\/syaro.hotococoa.moe\/wordpress\/?p=134","title":{"rendered":"\u4eceC++\u8c08\u591a\u6001"},"content":{"rendered":"

\u591a\u6001\uff08Polymorphism\uff09\u6307\u7684\u662f\u4e00\u79cd\u76f8\u540c\u7684\u5f62\u5f0f\uff08\u540d\u79f0\u548c\u64cd\u4f5c\u7b49\uff09\u8868\u73b0\u51fa\u4e0d\u540c\u884c\u4e3a\u7684\u6982\u5ff5\uff0c\u591a\u6001\u7684\u6982\u5ff5\u7531Christopher Strachey\u4e8e1967\u5e74[1]\u5b9a\u4e49\u4e3a\u4e24\u4e2a\u5206\u652f\uff1a\u7279\u8bbe\u578b\u591a\u6001\uff08Ad-hoc polymorphism\uff09\u548c\u901a\u7528\u578b\u591a\u6001\uff08Universal polymorphism\uff09\uff0c\u6b64\u5904\u7684\u7279\u8bbe\u4ec5\u4e0e\u901a\u7528\u76f8\u5bf9\uff0c\u5e76\u975e\u8d2c\u4e49\u7684\u3002\u7279\u8bbe\u578b\u591a\u6001\u5728\u4e4b\u540e\u53c8\u88ab\u7ec6\u5206\u4e3a\u7279\u8bbe\u5f3a\u5236\u591a\u6001\uff08Ad-hoc coercion polymorphism\uff09\u53ca\u7279\u8bbe\u91cd\u8f7d\u591a\u6001\uff08Ad-hoc overloading polymorphism\uff0c\u6709\u65f6\u5019\u4e5f\u7b80\u79f0\u4e3a\u7279\u8bbe\u591a\u6001\uff09\u4e24\u7c7b\uff0c\u901a\u7528\u578b\u591a\u6001\u4e5f\u88ab\u7ec6\u5206\u4e3a\u53c2\u6570\u591a\u6001\uff08Parametric polymorphism\uff09\u53ca\u5305\u542b\u591a\u6001\uff08Inclusion polymorphism\uff0c\u53c8\u79f0\u5b50\u7c7b\u578b\u591a\u6001 Subtyping polymorphism\uff09\u3002\u901a\u5e38\u5728 OOP \u7684\u8bed\u5883\u4e0b\u6211\u4eec\u6240\u6307\u7684\u591a\u6001\u90fd\u662f\u5305\u542b\u591a\u6001\uff0c\u8fd9\u540c\u6837\u4e5f\u662f C++ \u6807\u51c6\u4e2d[2]\u552f\u4e00\u63d0\u5230\u7684\u591a\u6001\u5f62\u5f0f\u3002<\/p>\n

\u7279\u8bbe\u5f3a\u5236\u591a\u6001\u4e2d\u7684\u5f3a\u5236\u6307\u7684\u662f\u9690\u5f0f<\/span>\u8f6c\u6362\u8fd9\u6837\u7684\u8bed\u4e49\u64cd\u4f5c\uff0c\u8fd9\u4f7f\u5f97\u671f\u671b\u67d0\u4e00\u7c7b\u578b\u7684\u5730\u65b9\u5141\u8bb8\u51fa\u73b0\u4e0d\u540c\u7684\u7c7b\u578b\u800c\u4e0d\u4f1a\u5bfc\u81f4\u9519\u8bef\uff0c\u63d0\u4f9b\u7684\u503c\u5c06\u4f1a\u8f6c\u6362\u5230\u671f\u671b\u7684\u7c7b\u578b\uff0c\u5728C++\u4e2d\u901a\u5e38\u7684\u8868\u73b0\u4e3a\uff1a<\/span><\/p>\n

int a = 1;\nfloat b = a; \/\/ a \u88ab\u9690\u5f0f\u8f6c\u6362\u4e3a float\uff0cb \u521d\u59cb\u5316\u4e3a\u8f6c\u6362\u800c\u6765\u7684\u503c\uff081.0f\uff09\nfloat c = a + b; \/\/ a \u88ab\u9690\u5f0f\u8f6c\u6362\u4e3a float \u4e0e b \u8fdb\u884c\u8fd0\u7b97<\/pre>\n
\u7279\u8bbe\u91cd\u8f7d\u591a\u6001\u4e2d\u7684\u91cd\u8f7d\u6307\u7684\u662f\u76f8\u540c\u7684\u540d\u79f0\uff08\u4ee5\u53ca\u64cd\u4f5c\u7b49\uff0c\u5982\u64cd\u4f5c\u7b26\u91cd\u8f7d\uff09\u5728\u63d0\u4f9b\u4e0d\u540c\u7c7b\u578b\u7684\u53c2\u6570\u4e4b\u65f6\u4f7f\u7528\u4e0d\u540c\u7684\u5b9e\u73b0\uff0c\u6a21\u677f\u7684\u7279\u5316\u540c\u6837\u53ef\u4ee5\u770b\u4f5c\u7279\u8bbe\u91cd\u8f7d\u591a\u6001\uff0c\u540c\u6837\u6211\u4eec\u901a\u8fc7\u4f8b\u5b50\u6765\u5c55\u73b0\u6b64\u591a\u6001\u5f62\u5f0f\uff1a<\/p>\n
int Add(int a, int b)\n{\n  return a + b;\n}\nfloat Add(float a, float b)\n{\n  return a + b;\n}\nstruct Vector2\n{\n  float X, Y;\n};\nVector2 Add(Vector2 a, Vector2 b)\n{\n  return { a.X + b.X, a.Y + b.Y };\n}\n\nint a = 1, b = 2;\nfloat c = 1.0f, d = 3.0f;\nVector2 e{ 1.0f, 2.0f }, f{ 2.0f, 3.0f };\n\n\/\/ \u4f7f\u7528\u7c7b\u578b\u7686\u4e3a int \u7684\u53c2\u6570\uff0c\u4ee5\u540d\u79f0 Add \u8c03\u7528\u51fd\u6570\u5c06\u4f1a\u5339\u914d\u5230\u7b2c\u4e00\u4e2a\u5b9e\u73b0\nconst int result1 = Add(a, b);\n\/\/ \u4f7f\u7528\u7c7b\u578b\u7686\u4e3a float \u7684\u53c2\u6570\uff0c\u4ee5\u540d\u79f0 Add \u8c03\u7528\u51fd\u6570\u5c06\u4f1a\u5339\u914d\u5230\u7b2c\u4e8c\u4e2a\u5b9e\u73b0\nconst float result2 = Add(c, d);\n\/\/ \u4f7f\u7528\u7c7b\u578b\u7686\u4e3a Vector2 \u7684\u53c2\u6570\uff0c\u4ee5\u540d\u79f0 Add \u8c03\u7528\u51fd\u6570\u5c06\u4f1a\u5339\u914d\u5230\u7b2c\u4e09\u4e2a\u5b9e\u73b0\nconst Vector2 result3 = Add(e, f);\n\/\/ \u5bf9\u4e8e\u4e0d\u540c\u7c7b\u578b\u7684\u53c2\u6570\uff0cAdd \u8868\u73b0\u51fa\u4e0d\u540c\u7684\u884c\u4e3a\uff0c\u8fd9\u4f53\u73b0\u4e86\u7279\u8bbe\u91cd\u8f7d\u591a\u6001<\/pre>\n
\u53c2\u6570\u591a\u6001\u5373\u501f\u7531\u9690\u5f0f\u6216\u663e\u5f0f\u7684\u53c2\u6570\uff0c\u4f7f\u5f97\u76f8\u540c\u540d\u79f0\u7684\u5b9e\u4f53\u8868\u73b0\u51fa\u4e0d\u540c\u884c\u4e3a\uff0cC++ \u4e2d\u7684\u76f4\u63a5\u4f53\u73b0\u5373\u662f\u6a21\u677f\uff0c\u4f53\u73b0\u6b64\u591a\u6001\u6027\u8d28\u7684\u6a21\u677f\u53ef\u80fd\u751f\u6210\u4e00\u7ec4\u51fd\u6570\u3001\u7c7b\u3001\u7c7b\u578b\u522b\u540d\u3001\u53d8\u91cf\u53ca\u6982\u5ff5\uff08Concept\uff09\uff0c\u8fd9\u6837\u7684\u6a21\u677f\u88ab\u5206\u522b\u79f0\u4e3a\u51fd\u6570\u6a21\u677f\u3001\u7c7b\u6a21\u677f\u3001\u522b\u540d\u6a21\u677f\u3001\u53d8\u91cf\u6a21\u677f\u53ca\u6982\u5ff5\uff0c\u5728\u5176\u4ed6\u540c\u6837\u5177\u6709\u53c2\u6570\u591a\u6001\u7684\u8bed\u8a00\u4e2d\u5bf9\u5e94\u51fd\u6570\u6a21\u677f\u53ca\u7c7b\u6a21\u677f\u7684\u6982\u5ff5\u591a\u88ab\u79f0\u4e3a\u6cdb\u578b\u51fd\u6570\u53ca\u6cdb\u578b\u7c7b\uff0c\u800c\u5bf9\u4e8e\u522b\u540d\u6a21\u677f\u3001\u53d8\u91cf\u6a21\u677f\u53ca\u6982\u5ff5\u51e0\u4e4e\u6ca1\u6709\u5176\u4ed6\u8bed\u8a00\u5177\u6709\u7c7b\u4f3c\u7684\u6982\u5ff5\uff1a<\/p>\n
template <typename T>\nT Add(T a, T b)\n{\n  return a + b;\n}\n\nint a = 1, b = 2;\nfloat c = 1.0f, d = 3.0f;\n\n\/\/ \u4e0d\u9700\u8981\u91cd\u590d\u7684\u4ee3\u7801\u4fbf\u53ef\u8fbe\u5230\u7279\u8bbe\u91cd\u8f7d\u591a\u6001\u4e2d\u7684\u4f8b\u5b50\u7684\u6548\u679c\uff0c\u4f46\u662f\u4e0d\u80fd\u5bf9\u6ca1\u6709\u91cd\u8f7d operator+ \u7684 Vector2 \u7c7b\u578b\u505a\u5230\u76f8\u540c\u7684\u4e8b\nconst int result1 = Add(a, b);\nconst float result2 = Add(c, d);\n\ntemplate <typename T>\nstruct Vector2\n{\n  T X, Y;\n  Vector2(T x, T y) : X{ x }, Y{ y }\n  {\n  }\n};\n\n\/\/ \u4e0d\u9700\u8981\u5bf9\u5bb9\u7eb3 int \u548c float \u7684 Vector2 \u90fd\u5199\u4e00\u4e2a\u5355\u72ec\u7684\u7c7b\n\/\/ \u4ece C++17 \u5f00\u59cb\u53ef\u4ee5\u5bf9\u4e00\u90e8\u5206\u7c7b\u6a21\u677f\u4e0d\u663e\u5f0f\u6307\u5b9a\u6a21\u677f\u53c2\u6570\u4e5f\u53ef\u5b9e\u4f8b\u5316\u5bf9\u5e94\u7684\u7c7b\u6a21\u677f\u4e86\n\/\/ v1 \u5177\u6709\u7c7b\u578b Vector2<int>\uff0cv2 \u5177\u6709\u7c7b\u578b Vector2<float>\nVector2 v1{ 1, 2 };\nVector2 v2{ 1.0f, 2.0f };<\/pre>\n
\u5305\u542b\u591a\u6001\u662f\u6700\u5e38\u88ab\u63d0\u5230\u7684\u591a\u6001\u5f62\u5f0f\uff0c\u4e5f\u5373\u5b50\u7c7b\u578b\u591a\u6001\uff0c\u6ce8\u610f\u5b50\u7c7b\u578b\uff08Subtyping\uff09\u4e0e\u7ee7\u627f\uff08Inheritance\uff09\u5e76\u975e\u7b49\u4ef7\u7684\u6982\u5ff5\uff0c\u5b50\u7c7b\u578b\u4e00\u822c\u662f\u7528\u4e8e\u8868\u8fbe\u63a5\u53e3\u7684\u517c\u5bb9\u6027\uff0c\u5373\u5f53\u6211\u4eec\u8bf4 B \u662f A \u7684\u5b50\u7c7b\u578b\u4e4b\u65f6\uff0c\u6211\u4eec\u6240\u8bf4\u7684\u662f\u5bf9\u4e8e A \u7684\u64cd\u4f5c\u90fd\u53ef\u4ee5\u5bf9 B \u8fdb\u884c\uff0c\u7ee7\u627f\u5219\u503e\u5411\u4e8e\u8868\u73b0\u5b9e\u73b0\u7684\u91cd\u7528\uff0c\u5373 B \u91cd\u7528 A \u7684\u64cd\u4f5c\u6765\u5b9e\u73b0\u81ea\u5df1\u7684\u64cd\u4f5c\uff0c\u5219 B \u7ee7\u627f\u81ea A [3]\u3002\u4f46\u5f88\u4e0d\u5e78\u5730\u7531\u4e8e\u592a\u591a\u8bed\u8a00\u6df7\u6dc6\u8fd9\u4e24\u4e2a\u6982\u5ff5\uff0c\u5f88\u5c11\u6709\u4eba\u80fd\u6b63\u786e\u5730\u533a\u5206\u5b83\u4eec\uff0c\u5305\u542b\u591a\u6001\u5728 C++ \u53ca\u591a\u6570\u5176\u4ed6\u8bed\u8a00\u4e2d\u4ee5\u7ee7\u627f\u7684\u65b9\u5f0f\u4f53\u73b0\uff1a<\/p>\n
struct Human\n{\n  string Name;\n  int Age;\n\n  Human(string name, int age) : Name{ move(name) }, Age{ age }\n  {\n  }\n\n  \/\/ \u901a\u5e38\u5bf9\u4e8e\u591a\u6001\u7684\u57fa\u7c7b\u9700\u8981\u516c\u6709\u7684\u865a\u6790\u6784\u51fd\u6570\uff0c\u6216\u8005\u4fdd\u62a4\u7684\u975e\u865a\u6790\u6784\u51fd\u6570\n  virtual ~Human() = default;\n  virtual string DescriptSelf()\n  {\n    return \"I'm\" + Name + \", \" + to_string(Age) + \" year(s) old.\";\n  }\n};\n\nstruct Student : Human\n{\n  string Class;\n\n  Student(string name, int age, string class_) : Human{ move(name), age }, Class{ move(class_) }\n  {\n  }\n\n  string DescriptSelf() override\n  {\n    return Human::DescriptSelf() + \" I'm a student from class \" + Class + \".\";\n  }\n};\n\nStudent a{ \"Chikyuu\", 24, \"Shimokitazawa\" };\nHuman b{ \"Case\", 10 };\nHuman* p = &a;\n\/\/ \u867d\u7136 p \u7684\u9759\u6001\u7c7b\u578b\u662f Human*\uff0c\u4f46\u6240\u6307\u5411\u7684\u5bf9\u8c61\u7684\u52a8\u6001\u7c7b\u578b\u662f Student\uff0c\u56e0\u6b64\u7ed3\u679c\u4e3a\u201cI'm Chikyuu, 24 year(s) old. I'm a student from class Shimokitazawa.\u201d\np->DescriptSelf();\np = &b;\n\/\/ p \u6240\u6307\u5411\u7684\u5bf9\u8c61\u7684\u52a8\u6001\u7c7b\u578b\u662f Human\uff0c\u8f93\u51fa\u4e3a\u201cI'm Case, 10 year(s) old.\u201d\np->DescriptSelf();<\/pre>\n
\u5f15\u7528\uff1a<\/p>\n
[1]\u00a0C. Strachey, Fundamental concepts in programming languages, Notes for the International Summer School in Computer Programming, Copenhagen (1967)<\/p>\n
[2] ISO\/IEC 14882:2017\u00a0[class.virtual]<\/p>\n
[3]\u00a0https:\/\/www.cmi.ac.in\/~madhavan\/courses\/pl2006\/lecturenotes\/lecture-notes\/node28.html<\/a><\/p>\n","protected":false},"excerpt":{"rendered":"
\u591a\u6001\uff08Polymorphism\uff09\u6307\u7684\u662f\u4e00\u79cd\u76f8\u540c\u7684\u5f62\u5f0f\uff08\u540d\u79f0\u548c\u64cd\u4f5c\u7b49\uff09\u8868\u73b0\u51fa\u4e0d\u540c\u884c\u4e3a\u7684\u6982\u5ff5\uff0c\u591a\u6001\u7684\u6982\u5ff5\u7531Chri … <\/p>\n
\u7ee7\u7eed\u9605\u8bfb\u201c\u4eceC++\u8c08\u591a\u6001\u201d<\/span><\/a><\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"jetpack_post_was_ever_published":false,"_jetpack_newsletter_access":"","_jetpack_dont_email_post_to_subs":false,"_jetpack_newsletter_tier_id":0,"_jetpack_memberships_contains_paywalled_content":false,"_jetpack_memberships_contains_paid_content":false,"footnotes":"","jetpack_publicize_message":"","jetpack_publicize_feature_enabled":true,"jetpack_social_post_already_shared":true,"jetpack_social_options":{"image_generator_settings":{"template":"highway","default_image_id":0,"font":"","enabled":false},"version":2}},"categories":[5],"tags":[],"class_list":["post-134","post","type-post","status-publish","format-standard","hentry","category-5"],"jetpack_publicize_connections":[],"jetpack_featured_media_url":"","jetpack_sharing_enabled":true,"jetpack_shortlink":"https:\/\/wp.me\/p9CzIN-2a","jetpack_likes_enabled":true,"jetpack-related-posts":[{"id":67,"url":"https:\/\/syaro.hotococoa.moe\/wordpress\/?p=67","url_meta":{"origin":134,"position":0},"title":"\u8bb0\u4e00\u4e9b\u81ea\u5df1\u9047\u5230\u7684\u5751","author":"Chino","date":"2018\u5e741\u670826\u65e5","format":false,"excerpt":"\u7c7b\u5185\u5305\u542b\u975e\u9759\u6001\u7684\u53f3\u503c\u5f15\u7528\u6210\u5458\u65f6\u9690\u5f0f\u751f\u6210\u7684\u590d\u5236\u6784\u9020\u51fd\u6570\u662fdelete\u7684\uff0c\u4f46\u662f\u79fb\u52a8\u6784\u9020\u6b63\u5e38\uff0c\u56e0\u6b64\u5305\u542b\u53f3\u503c\u2026","rel":"","context":"\u5728\u201c\u8e29\u5751\u201d\u4e2d","block_context":{"text":"\u8e29\u5751","link":"https:\/\/syaro.hotococoa.moe\/wordpress\/?cat=6"},"img":{"alt_text":"","src":"","width":0,"height":0},"classes":[]},{"id":253,"url":"https:\/\/syaro.hotococoa.moe\/wordpress\/?p=253","url_meta":{"origin":134,"position":1},"title":"LLVM\u5faa\u73af\u672f\u8bed\uff08\u548c\u89c4\u8303\u5f62\u5f0f\uff09","author":"Chino","date":"2020\u5e744\u670824\u65e5","format":false,"excerpt":"\u539f\u6587\u94fe\u63a5\uff1aLLVM 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