{"id":2964,"date":"2020-12-21T12:44:17","date_gmt":"2020-12-21T04:44:17","guid":{"rendered":"http:\/\/blog.coolcoding.cn\/?p=2964"},"modified":"2020-12-21T12:44:24","modified_gmt":"2020-12-21T04:44:24","slug":"c%e5%8f%af%e5%8f%98%e6%a8%a1%e7%89%88%e5%8f%82%e6%95%b0","status":"publish","type":"post","link":"https:\/\/blog.coolcoding.cn\/?p=2964","title":{"rendered":"C++\u53ef\u53d8\u6a21\u7248\u53c2\u6570"},"content":{"rendered":"\n

1\u6982\u8ff0<\/strong><\/h2>\n\n\n\n

C++11\u7684\u65b0\u7279\u6027–\u53ef\u53d8\u6a21\u7248\u53c2\u6570\uff08variadic templates\uff09\u662fC++11\u65b0\u589e\u7684\u6700\u5f3a\u5927\u7684\u7279\u6027\u4e4b\u4e00\uff0c\u5b83\u5bf9\u53c2\u6570\u8fdb\u884c\u4e86\u9ad8\u5ea6\u6cdb\u5316\uff0c\u5b83\u80fd\u8868\u793a0\u5230\u4efb\u610f\u4e2a\u6570\u3001\u4efb\u610f\u7c7b\u578b\u7684\u53c2\u6570\u3002\u76f8\u6bd4C++98\/03\uff0c\u7c7b\u6a21\u7248\u548c\u51fd\u6570\u6a21\u7248\u4e2d\u53ea\u80fd\u542b\u56fa\u5b9a\u6570\u91cf\u7684\u6a21\u7248\u53c2\u6570\uff0c\u53ef\u53d8\u6a21\u7248\u53c2\u6570\u65e0\u7591\u662f\u4e00\u4e2a\u5de8\u5927\u7684\u6539\u8fdb\u3002\u7136\u800c\u7531\u4e8e\u53ef\u53d8\u6a21\u7248\u53c2\u6570\u6bd4\u8f83\u62bd\u8c61\uff0c\u4f7f\u7528\u8d77\u6765\u9700\u8981\u4e00\u5b9a\u7684\u6280\u5de7\uff0c\u6240\u4ee5\u5b83\u4e5f\u662fC++11\u4e2d\u6700\u96be\u7406\u89e3\u548c\u638c\u63e1\u7684\u7279\u6027\u4e4b\u4e00\u3002\u867d\u7136\u638c\u63e1\u53ef\u53d8\u6a21\u7248\u53c2\u6570\u6709\u4e00\u5b9a\u96be\u5ea6\uff0c\u4f46\u662f\u5b83\u5374\u662fC++11\u4e2d\u6700\u6709\u610f\u601d\u7684\u4e00\u4e2a\u7279\u6027\uff0c\u672c\u6587\u5e0c\u671b\u5e26\u9886\u8bfb\u8005\u7531\u6d45\u5165\u6df1\u7684\u8ba4\u8bc6\u548c\u638c\u63e1\u8fd9\u4e00\u7279\u6027\uff0c\u540c\u65f6\u4e5f\u4f1a\u901a\u8fc7\u4e00\u4e9b\u5b9e\u4f8b\u6765\u5c55\u793a\u53ef\u53d8\u53c2\u6570\u6a21\u7248\u7684\u4e00\u4e9b\u7528\u6cd5\u3002<\/p>\n\n\n\n

2\u53ef\u53d8\u6a21\u7248\u53c2\u6570\u7684\u5c55\u5f00<\/strong><\/h2>\n\n\n\n

\u53ef\u53d8\u53c2\u6570\u6a21\u677f\u548c\u666e\u901a\u6a21\u677f\u7684\u8bed\u4e49\u662f\u4e00\u6837\u7684\uff0c\u53ea\u662f\u5199\u6cd5\u4e0a\u7a0d\u6709\u533a\u522b\uff0c\u58f0\u660e\u53ef\u53d8\u53c2\u6570\u6a21\u677f\u65f6\u9700\u8981\u5728typename\u6216class\u540e\u9762\u5e26\u4e0a\u7701\u7565\u53f7\u201c…\u201d\u3002\u6bd4\u5982\u6211\u4eec\u5e38\u5e38\u8fd9\u6837\u58f0\u660e\u4e00\u4e2a\u53ef\u53d8\u6a21\u7248\u53c2\u6570\uff1atemplate<typename…>\u6216\u8005template<class…>\uff0c\u4e00\u4e2a\u5178\u578b\u7684\u53ef\u53d8\u6a21\u7248\u53c2\u6570\u7684\u5b9a\u4e49\u662f\u8fd9\u6837\u7684\uff1a<\/p>\n\n\n\n

template <class... T>\nvoid f(T... args);<\/pre>\n\n\n\n
\u3000\u3000\u4e0a\u9762\u7684\u53ef\u53d8\u6a21\u7248\u53c2\u6570\u7684\u5b9a\u4e49\u5f53\u4e2d\uff0c\u7701\u7565\u53f7\u7684\u4f5c\u7528\u6709\u4e24\u4e2a\uff1a
1.\u58f0\u660e\u4e00\u4e2a\u53c2\u6570\u5305T… args\uff0c\u8fd9\u4e2a\u53c2\u6570\u5305\u4e2d\u53ef\u4ee5\u5305\u542b0\u5230\u4efb\u610f\u4e2a\u6a21\u677f\u53c2\u6570\uff1b
2.\u5728\u6a21\u677f\u5b9a\u4e49\u7684\u53f3\u8fb9\uff0c\u53ef\u4ee5\u5c06\u53c2\u6570\u5305\u5c55\u5f00\u6210\u4e00\u4e2a\u4e00\u4e2a\u72ec\u7acb\u7684\u53c2\u6570\u3002<\/p>\n\n\n\n
\u3000\u3000\u4e0a\u9762\u7684\u53c2\u6570args\u524d\u9762\u6709\u7701\u7565\u53f7\uff0c\u6240\u4ee5\u5b83\u5c31\u662f\u4e00\u4e2a\u53ef\u53d8\u6a21\u7248\u53c2\u6570\uff0c\u6211\u4eec\u628a\u5e26\u7701\u7565\u53f7\u7684\u53c2\u6570\u79f0\u4e3a\u201c\u53c2\u6570\u5305\u201d\uff0c\u5b83\u91cc\u9762\u5305\u542b\u4e860\u5230N\uff08N>=0\uff09\u4e2a\u6a21\u7248\u53c2\u6570\u3002\u6211\u4eec\u65e0\u6cd5\u76f4\u63a5\u83b7\u53d6\u53c2\u6570\u5305args\u4e2d\u7684\u6bcf\u4e2a\u53c2\u6570\u7684\uff0c\u53ea\u80fd\u901a\u8fc7\u5c55\u5f00\u53c2\u6570\u5305\u7684\u65b9\u5f0f\u6765\u83b7\u53d6\u53c2\u6570\u5305\u4e2d\u7684\u6bcf\u4e2a\u53c2\u6570\uff0c\u8fd9\u662f\u4f7f\u7528\u53ef\u53d8\u6a21\u7248\u53c2\u6570\u7684\u4e00\u4e2a\u4e3b\u8981\u7279\u70b9\uff0c\u4e5f\u662f\u6700\u5927\u7684\u96be\u70b9\uff0c\u5373\u5982\u4f55\u5c55\u5f00\u53ef\u53d8\u6a21\u7248\u53c2\u6570\u3002<\/p>\n\n\n\n
\u3000\u3000\u53ef\u53d8\u6a21\u7248\u53c2\u6570\u548c\u666e\u901a\u7684\u6a21\u7248\u53c2\u6570\u8bed\u4e49\u662f\u4e00\u81f4\u7684\uff0c\u6240\u4ee5\u53ef\u4ee5\u5e94\u7528\u4e8e\u51fd\u6570\u548c\u7c7b\uff0c\u5373\u53ef\u53d8\u6a21\u7248\u53c2\u6570\u51fd\u6570\u548c\u53ef\u53d8\u6a21\u7248\u53c2\u6570\u7c7b\uff0c\u7136\u800c\uff0c\u6a21\u7248\u51fd\u6570\u4e0d\u652f\u6301\u504f\u7279\u5316\uff0c\u6240\u4ee5\u53ef\u53d8\u6a21\u7248\u53c2\u6570\u51fd\u6570\u548c\u53ef\u53d8\u6a21\u7248\u53c2\u6570\u7c7b\u5c55\u5f00\u53ef\u53d8\u6a21\u7248\u53c2\u6570\u7684\u65b9\u6cd5\u8fd8\u4e0d\u5c3d\u76f8\u540c\uff0c\u4e0b\u9762\u6211\u4eec\u6765\u5206\u522b\u770b\u770b\u4ed6\u4eec\u5c55\u5f00\u53ef\u53d8\u6a21\u7248\u53c2\u6570\u7684\u65b9\u6cd5\u3002<\/p>\n\n\n\n
2.1\u53ef\u53d8\u6a21\u7248\u53c2\u6570\u51fd\u6570<\/strong><\/h3>\n\n\n\n
\u4e00\u4e2a\u7b80\u5355\u7684\u53ef\u53d8\u6a21\u7248\u53c2\u6570\u51fd\u6570\uff1a<\/p>\n\n\n\n
template <class... T>\nvoid f(T... args)\n{    \n    cout << sizeof...(args) << endl; \/\/\u6253\u5370\u53d8\u53c2\u7684\u4e2a\u6570\n}\n\nf();        \/\/0\nf(1, 2);    \/\/2\nf(1, 2.5, \"\");    \/\/3<\/pre>\n\n\n\n
\u4e0a\u9762\u7684\u4f8b\u5b50\u4e2d\uff0cf()\u6ca1\u6709\u4f20\u5165\u53c2\u6570\uff0c\u6240\u4ee5\u53c2\u6570\u5305\u4e3a\u7a7a\uff0c\u8f93\u51fa\u7684size\u4e3a0\uff0c\u540e\u9762\u4e24\u6b21\u8c03\u7528\u5206\u522b\u4f20\u5165\u4e24\u4e2a\u548c\u4e09\u4e2a\u53c2\u6570\uff0c\u6545\u8f93\u51fa\u7684size\u5206\u522b\u4e3a2\u548c3\u3002\u7531\u4e8e\u53ef\u53d8\u6a21\u7248\u53c2\u6570\u7684\u7c7b\u578b\u548c\u4e2a\u6570\u662f\u4e0d\u56fa\u5b9a\u7684\uff0c\u6240\u4ee5\u6211\u4eec\u53ef\u4ee5\u4f20\u4efb\u610f\u7c7b\u578b\u548c\u4e2a\u6570\u7684\u53c2\u6570\u7ed9\u51fd\u6570f\u3002\u8fd9\u4e2a\u4f8b\u5b50\u53ea\u662f\u7b80\u5355\u7684\u5c06\u53ef\u53d8\u6a21\u7248\u53c2\u6570\u7684\u4e2a\u6570\u6253\u5370\u51fa\u6765\uff0c\u5982\u679c\u6211\u4eec\u9700\u8981\u5c06\u53c2\u6570\u5305\u4e2d\u7684\u6bcf\u4e2a\u53c2\u6570\u6253\u5370\u51fa\u6765\u7684\u8bdd\u5c31\u9700\u8981\u901a\u8fc7\u4e00\u4e9b\u65b9\u6cd5\u4e86\u3002\u5c55\u5f00\u53ef\u53d8\u6a21\u7248\u53c2\u6570\u51fd\u6570\u7684\u65b9\u6cd5\u4e00\u822c\u6709\u4e24\u79cd\uff1a\u4e00\u79cd\u662f\u901a\u8fc7\u9012\u5f52\u51fd\u6570\u6765\u5c55\u5f00\u53c2\u6570\u5305\uff0c\u53e6\u5916\u4e00\u79cd\u662f\u901a\u8fc7\u9017\u53f7\u8868\u8fbe\u5f0f\u6765\u5c55\u5f00\u53c2\u6570\u5305\u3002\u4e0b\u9762\u6765\u770b\u770b\u5982\u4f55\u7528\u8fd9\u4e24\u79cd\u65b9\u6cd5\u6765\u5c55\u5f00\u53c2\u6570\u5305\u3002<\/p>\n\n\n\n
2.1.1\u9012\u5f52\u51fd\u6570\u65b9\u5f0f\u5c55\u5f00\u53c2\u6570\u5305<\/strong><\/h4>\n\n\n\n
\u901a\u8fc7\u9012\u5f52\u51fd\u6570\u5c55\u5f00\u53c2\u6570\u5305\uff0c\u9700\u8981\u63d0\u4f9b\u4e00\u4e2a\u53c2\u6570\u5305\u5c55\u5f00\u7684\u51fd\u6570\u548c\u4e00\u4e2a\u9012\u5f52\u7ec8\u6b62\u51fd\u6570\uff0c\u9012\u5f52\u7ec8\u6b62\u51fd\u6570\u6b63\u662f\u7528\u6765\u7ec8\u6b62\u9012\u5f52\u7684\uff0c\u6765\u770b\u770b\u4e0b\u9762\u7684\u4f8b\u5b50\u3002<\/p>\n\n\n\n
#include <iostream>\nusing namespace std;\n\/\/\u9012\u5f52\u7ec8\u6b62\u51fd\u6570\nvoid print()\n{\n   cout << \"empty\" << endl;\n}\n\/\/\u5c55\u5f00\u51fd\u6570\ntemplate <class T, class ...Args>\nvoid print(T head, Args... rest)\n{\n   cout << \"parameter \" << head << endl;\n   print(rest...);\n}\n\n\nint main(void)\n{\n   print(1,2,3,4);\n   return 0;\n}<\/pre>\n\n\n\n
\u4e0a\u4f8b\u4f1a\u8f93\u51fa\u6bcf\u4e00\u4e2a\u53c2\u6570\uff0c\u76f4\u5230\u4e3a\u7a7a\u65f6\u8f93\u51faempty\u3002\u5c55\u5f00\u53c2\u6570\u5305\u7684\u51fd\u6570\u6709\u4e24\u4e2a\uff0c\u4e00\u4e2a\u662f\u9012\u5f52\u51fd\u6570\uff0c\u53e6\u5916\u4e00\u4e2a\u662f\u9012\u5f52\u7ec8\u6b62\u51fd\u6570\uff0c\u53c2\u6570\u5305Args…\u5728\u5c55\u5f00\u7684\u8fc7\u7a0b\u4e2d\u9012\u5f52\u8c03\u7528\u81ea\u5df1\uff0c\u6bcf\u8c03\u7528\u4e00\u6b21\u53c2\u6570\u5305\u4e2d\u7684\u53c2\u6570\u5c31\u4f1a\u5c11\u4e00\u4e2a\uff0c\u76f4\u5230\u6240\u6709\u7684\u53c2\u6570\u90fd\u5c55\u5f00\u4e3a\u6b62\uff0c\u5f53\u6ca1\u6709\u53c2\u6570\u65f6\uff0c\u5219\u8c03\u7528\u975e\u6a21\u677f\u51fd\u6570print\u7ec8\u6b62\u9012\u5f52\u8fc7\u7a0b\u3002<\/p>\n\n\n\n
\u9012\u5f52\u8c03\u7528\u7684\u8fc7\u7a0b\u662f\u8fd9\u6837\u7684:<\/p>\n\n\n\n
print(1,2,3,4);\nprint(2,3,4);\nprint(3,4);\nprint(4);\nprint();<\/pre>\n\n\n\n
\u4e0a\u9762\u7684\u9012\u5f52\u7ec8\u6b62\u51fd\u6570\u8fd8\u53ef\u4ee5\u5199\u6210\u8fd9\u6837\uff1a<\/p>\n\n\n\n
template <class T>\nvoid print(T t)\n{\n   cout << t << endl;\n}<\/pre>\n\n\n\n
\u4fee\u6539\u9012\u5f52\u7ec8\u6b62\u51fd\u6570\u540e\uff0c\u4e0a\u4f8b\u4e2d\u7684\u8c03\u7528\u8fc7\u7a0b\u662f\u8fd9\u6837\u7684\uff1a<\/p>\n\n\n\n
print(1,2,3,4);\nprint(2,3,4);\nprint(3,4);\nprint(4);<\/pre>\n\n\n\n
\u5f53\u53c2\u6570\u5305\u5c55\u5f00\u5230\u6700\u540e\u4e00\u4e2a\u53c2\u6570\u65f6\u9012\u5f52\u4e3a\u6b62\u3002\u518d\u770b\u4e00\u4e2a\u901a\u8fc7\u53ef\u53d8\u6a21\u7248\u53c2\u6570\u6c42\u548c\u7684\u4f8b\u5b50\uff1a<\/p>\n\n\n\n
template<typename T>\nT sum(T t)\n{\n    return t;\n}\ntemplate<typename T, typename ... Types>\nT sum (T first, Types ... rest)\n{\n    return first + sum<T>(rest...);\n}\n\nsum(1,2,3,4); \/\/10<\/pre>\n\n\n\n
sum\u5728\u5c55\u5f00\u53c2\u6570\u5305\u7684\u8fc7\u7a0b\u4e2d\u5c06\u5404\u4e2a\u53c2\u6570\u76f8\u52a0\u6c42\u548c\uff0c\u53c2\u6570\u7684\u5c55\u5f00\u65b9\u5f0f\u548c\u524d\u9762\u7684\u6253\u5370\u53c2\u6570\u5305\u7684\u65b9\u5f0f\u662f\u4e00\u6837\u7684\u3002<\/p>\n\n\n\n
2.1.2\u9017\u53f7\u8868\u8fbe\u5f0f\u5c55\u5f00\u53c2\u6570\u5305<\/strong><\/h4>\n\n\n\n
\u9012\u5f52\u51fd\u6570\u5c55\u5f00\u53c2\u6570\u5305\u662f\u4e00\u79cd\u6807\u51c6\u505a\u6cd5\uff0c\u4e5f\u6bd4\u8f83\u597d\u7406\u89e3\uff0c\u4f46\u4e5f\u6709\u4e00\u4e2a\u7f3a\u70b9,\u5c31\u662f\u5fc5\u987b\u8981\u4e00\u4e2a\u91cd\u8f7d\u7684\u9012\u5f52\u7ec8\u6b62\u51fd\u6570\uff0c\u5373\u5fc5\u987b\u8981\u6709\u4e00\u4e2a\u540c\u540d\u7684\u7ec8\u6b62\u51fd\u6570\u6765\u7ec8\u6b62\u9012\u5f52\uff0c\u8fd9\u6837\u53ef\u80fd\u4f1a\u611f\u89c9\u7a0d\u6709\u4e0d\u4fbf\u3002\u6709\u6ca1\u6709\u4e00\u79cd\u66f4\u7b80\u5355\u7684\u65b9\u5f0f\u5462\uff1f\u5176\u5b9e\u8fd8\u6709\u4e00\u79cd\u65b9\u6cd5\u53ef\u4ee5\u4e0d\u901a\u8fc7\u9012\u5f52\u65b9\u5f0f\u6765\u5c55\u5f00\u53c2\u6570\u5305\uff0c\u8fd9\u79cd\u65b9\u5f0f\u9700\u8981\u501f\u52a9\u9017\u53f7\u8868\u8fbe\u5f0f\u548c\u521d\u59cb\u5316\u5217\u8868\u3002\u6bd4\u5982\u524d\u9762print\u7684\u4f8b\u5b50\u53ef\u4ee5\u6539\u6210\u8fd9\u6837\uff1a<\/p>\n\n\n\n
template <class T>\nvoid printarg(T t)\n{\n   cout << t << endl;\n}\n\ntemplate <class ...Args>\nvoid expand(Args... args)\n{\n   int arr[] = {(printarg(args), 0)...};\n}\n\nexpand(1,2,3,4);<\/pre>\n\n\n\n
\u8fd9\u4e2a\u4f8b\u5b50\u5c06\u5206\u522b\u6253\u5370\u51fa1,2,3,4\u56db\u4e2a\u6570\u5b57\u3002\u8fd9\u79cd\u5c55\u5f00\u53c2\u6570\u5305\u7684\u65b9\u5f0f\uff0c\u4e0d\u9700\u8981\u901a\u8fc7\u9012\u5f52\u7ec8\u6b62\u51fd\u6570\uff0c\u662f\u76f4\u63a5\u5728expand\u51fd\u6570\u4f53\u4e2d\u5c55\u5f00\u7684, printarg\u4e0d\u662f\u4e00\u4e2a\u9012\u5f52\u7ec8\u6b62\u51fd\u6570\uff0c\u53ea\u662f\u4e00\u4e2a\u5904\u7406\u53c2\u6570\u5305\u4e2d\u6bcf\u4e00\u4e2a\u53c2\u6570\u7684\u51fd\u6570\u3002\u8fd9\u79cd\u5c31\u5730\u5c55\u5f00\u53c2\u6570\u5305\u7684\u65b9\u5f0f\u5b9e\u73b0\u7684\u5173\u952e\u662f\u9017\u53f7\u8868\u8fbe\u5f0f\u3002\u6211\u4eec\u77e5\u9053\u9017\u53f7\u8868\u8fbe\u5f0f\u4f1a\u6309\u987a\u5e8f\u6267\u884c\u9017\u53f7\u524d\u9762\u7684\u8868\u8fbe\u5f0f\uff0c\u6bd4\u5982\uff1a<\/p>\n\n\n\n
d = (a = b, c); <\/pre>\n\n\n\n
\u8fd9\u4e2a\u8868\u8fbe\u5f0f\u4f1a\u6309\u987a\u5e8f\u6267\u884c\uff1ab\u4f1a\u5148\u8d4b\u503c\u7ed9a\uff0c\u63a5\u7740\u62ec\u53f7\u4e2d\u7684\u9017\u53f7\u8868\u8fbe\u5f0f\u8fd4\u56dec\u7684\u503c\uff0c\u56e0\u6b64d\u5c06\u7b49\u4e8ec\u3002<\/p>\n\n\n\n
expand\u51fd\u6570\u4e2d\u7684\u9017\u53f7\u8868\u8fbe\u5f0f\uff1a(printarg(args), 0)\uff0c\u4e5f\u662f\u6309\u7167\u8fd9\u4e2a\u6267\u884c\u987a\u5e8f\uff0c\u5148\u6267\u884cprintarg(args)\uff0c\u518d\u5f97\u5230\u9017\u53f7\u8868\u8fbe\u5f0f\u7684\u7ed3\u679c0\u3002\u540c\u65f6\u8fd8\u7528\u5230\u4e86C++11\u7684\u53e6\u5916\u4e00\u4e2a\u7279\u6027\u2014\u2014\u521d\u59cb\u5316\u5217\u8868\uff0c\u901a\u8fc7\u521d\u59cb\u5316\u5217\u8868\u6765\u521d\u59cb\u5316\u4e00\u4e2a\u53d8\u957f\u6570\u7ec4, {(printarg(args), 0)…}\u5c06\u4f1a\u5c55\u5f00\u6210((printarg(arg1),0), (printarg(arg2),0), (printarg(arg3),0),  etc… )\uff0c\u6700\u7ec8\u4f1a\u521b\u5efa\u4e00\u4e2a\u5143\u7d20\u503c\u90fd\u4e3a0\u7684\u6570\u7ec4int arr[sizeof…(Args)]\u3002\u7531\u4e8e\u662f\u9017\u53f7\u8868\u8fbe\u5f0f\uff0c\u5728\u521b\u5efa\u6570\u7ec4\u7684\u8fc7\u7a0b\u4e2d\u4f1a\u5148\u6267\u884c\u9017\u53f7\u8868\u8fbe\u5f0f\u524d\u9762\u7684\u90e8\u5206printarg(args)\u6253\u5370\u51fa\u53c2\u6570\uff0c\u4e5f\u5c31\u662f\u8bf4\u5728\u6784\u9020int\u6570\u7ec4\u7684\u8fc7\u7a0b\u4e2d\u5c31\u5c06\u53c2\u6570\u5305\u5c55\u5f00\u4e86\uff0c\u8fd9\u4e2a\u6570\u7ec4\u7684\u76ee\u7684\u7eaf\u7cb9\u662f\u4e3a\u4e86\u5728\u6570\u7ec4\u6784\u9020\u7684\u8fc7\u7a0b\u5c55\u5f00\u53c2\u6570\u5305\u3002\u6211\u4eec\u53ef\u4ee5\u628a\u4e0a\u9762\u7684\u4f8b\u5b50\u518d\u8fdb\u4e00\u6b65\u6539\u8fdb\u4e00\u4e0b\uff0c\u5c06\u51fd\u6570\u4f5c\u4e3a\u53c2\u6570\uff0c\u5c31\u53ef\u4ee5\u652f\u6301lambda\u8868\u8fbe\u5f0f\u4e86\uff0c\u4ece\u800c\u53ef\u4ee5\u5c11\u5199\u4e00\u4e2a\u9012\u5f52\u7ec8\u6b62\u51fd\u6570\u4e86\uff0c\u5177\u4f53\u4ee3\u7801\u5982\u4e0b\uff1a<\/p>\n\n\n\n
template<class F, class... Args>void expand(const F& f, Args&&...args) \n{\n  \/\/\u8fd9\u91cc\u7528\u5230\u4e86\u5b8c\u7f8e\u8f6c\u53d1\uff0c\u5173\u4e8e\u5b8c\u7f8e\u8f6c\u53d1\uff0c\u8bfb\u8005\u53ef\u4ee5\u53c2\u8003\u7b14\u8005\u5728\u4e0a\u4e00\u671f\u7a0b\u5e8f\u5458\u4e2d\u7684\u6587\u7ae0\u300a\u901a\u8fc74\u884c\u4ee3\u7801\u770b\u53f3\u503c\u5f15\u7528\u300b\n  initializer_list<int>{(f(std::forward< Args>(args)),0)...};\n}\nexpand([](int i){cout<<i<<endl;}, 1,2,3);<\/pre>\n\n\n\n
\u4e0a\u9762\u7684\u4f8b\u5b50\u5c06\u6253\u5370\u51fa\u6bcf\u4e2a\u53c2\u6570\uff0c\u8fd9\u91cc\u5982\u679c\u518d\u4f7f\u7528C++14\u7684\u65b0\u7279\u6027\u6cdb\u578blambda\u8868\u8fbe\u5f0f\u7684\u8bdd\uff0c\u53ef\u4ee5\u5199\u66f4\u6cdb\u5316\u7684lambda\u8868\u8fbe\u5f0f\u4e86\uff1a<\/p>\n\n\n\n
expand([](auto i){cout<<i<<endl;}, 1,2.0,\u201dtest\u201d);<\/pre>\n\n\n\n
2.2\u53ef\u53d8\u6a21\u7248\u53c2\u6570\u7c7b<\/strong><\/h3>\n\n\n\n
\u53ef\u53d8\u53c2\u6570\u6a21\u677f\u7c7b\u662f\u4e00\u4e2a\u5e26\u53ef\u53d8\u6a21\u677f\u53c2\u6570\u7684\u6a21\u677f\u7c7b\uff0c\u6bd4\u5982C++11\u4e2d\u7684\u5143\u7956std::tuple\u5c31\u662f\u4e00\u4e2a\u53ef\u53d8\u6a21\u677f\u7c7b\uff0c\u5b83\u7684\u5b9a\u4e49\u5982\u4e0b\uff1a<\/p>\n\n\n\n
template< class... Types >\nclass tuple;<\/pre>\n\n\n\n
\u8fd9\u4e2a\u53ef\u53d8\u53c2\u6570\u6a21\u677f\u7c7b\u53ef\u4ee5\u643a\u5e26\u4efb\u610f\u7c7b\u578b\u4efb\u610f\u4e2a\u6570\u7684\u6a21\u677f\u53c2\u6570\uff1a<\/p>\n\n\n\n
std::tuple<int> tp1 = std::make_tuple(1);\nstd::tuple<int, double> tp2 = std::make_tuple(1, 2.5);\nstd::tuple<int, double, string> tp3 = std::make_tuple(1, 2.5, \u201c\u201d);<\/pre>\n\n\n\n
\u53ef\u53d8\u53c2\u6570\u6a21\u677f\u7684\u6a21\u677f\u53c2\u6570\u4e2a\u6570\u53ef\u4ee5\u4e3a0\u4e2a\uff0c\u6240\u4ee5\u4e0b\u9762\u7684\u5b9a\u4e49\u4e5f\u662f\u4e5f\u662f\u5408\u6cd5\u7684\uff1a<\/p>\n\n\n\n
std::tuple<> tp;<\/pre>\n\n\n\n
\u53ef\u53d8\u53c2\u6570\u6a21\u677f\u7c7b\u7684\u53c2\u6570\u5305\u5c55\u5f00\u7684\u65b9\u5f0f\u548c\u53ef\u53d8\u53c2\u6570\u6a21\u677f\u51fd\u6570\u7684\u5c55\u5f00\u65b9\u5f0f\u4e0d\u540c\uff0c\u53ef\u53d8\u53c2\u6570\u6a21\u677f\u7c7b\u7684\u53c2\u6570\u5305\u5c55\u5f00\u9700\u8981\u901a\u8fc7\u6a21\u677f\u7279\u5316\u548c\u7ee7\u627f\u65b9\u5f0f\u53bb\u5c55\u5f00\uff0c\u5c55\u5f00\u65b9\u5f0f\u6bd4\u53ef\u53d8\u53c2\u6570\u6a21\u677f\u51fd\u6570\u8981\u590d\u6742\u3002\u4e0b\u9762\u6211\u4eec\u6765\u770b\u4e00\u4e0b\u5c55\u5f00\u53ef\u53d8\u6a21\u7248\u53c2\u6570\u7c7b\u4e2d\u7684\u53c2\u6570\u5305\u7684\u65b9\u6cd5\u3002<\/p>\n\n\n\n
2.2.1\u6a21\u7248\u504f\u7279\u5316\u548c\u9012\u5f52\u65b9\u5f0f\u6765\u5c55\u5f00\u53c2\u6570\u5305<\/strong><\/h4>\n\n\n\n
\u53ef\u53d8\u53c2\u6570\u6a21\u677f\u7c7b\u7684\u5c55\u5f00\u4e00\u822c\u9700\u8981\u5b9a\u4e49\u4e24\u5230\u4e09\u4e2a\u7c7b\uff0c\u5305\u62ec\u7c7b\u58f0\u660e\u548c\u504f\u7279\u5316\u7684\u6a21\u677f\u7c7b\u3002\u5982\u4e0b\u65b9\u5f0f\u5b9a\u4e49\u4e86\u4e00\u4e2a\u57fa\u672c\u7684\u53ef\u53d8\u53c2\u6570\u6a21\u677f\u7c7b\uff1a<\/p>\n\n\n\n
\/\/\u524d\u5411\u58f0\u660e\ntemplate<typename... Args>\nstruct Sum;\n\n\/\/\u57fa\u672c\u5b9a\u4e49\ntemplate<typename First, typename... Rest>\nstruct Sum<First, Rest...>\n{\n    enum { value = Sum<First>::value + Sum<Rest...>::value };\n};\n\n\/\/\u9012\u5f52\u7ec8\u6b62\ntemplate<typename Last>\nstruct Sum<Last>\n{\n    enum { value = sizeof (Last) };\n};<\/pre>\n\n\n\n
\u3000\u3000\u8fd9\u4e2aSum\u7c7b\u7684\u4f5c\u7528\u662f\u5728\u7f16\u8bd1\u671f\u8ba1\u7b97\u51fa\u53c2\u6570\u5305\u4e2d\u53c2\u6570\u7c7b\u578b\u7684size\u4e4b\u548c\uff0c\u901a\u8fc7sum<int,double,short>::value\u5c31\u53ef\u4ee5\u83b7\u53d6\u8fd93\u4e2a\u7c7b\u578b\u7684size\u4e4b\u548c\u4e3a14\u3002\u8fd9\u662f\u4e00\u4e2a\u7b80\u5355\u7684\u901a\u8fc7\u53ef\u53d8\u53c2\u6570\u6a21\u677f\u7c7b\u8ba1\u7b97\u7684\u4f8b\u5b50\uff0c\u53ef\u4ee5\u770b\u5230\u4e00\u4e2a\u57fa\u672c\u7684\u53ef\u53d8\u53c2\u6570\u6a21\u677f\u5e94\u7528\u7c7b\u7531\u4e09\u90e8\u5206\u7ec4\u6210\uff0c\u7b2c\u4e00\u90e8\u5206\u662f\uff1a<\/p>\n\n\n\n
template<typename... Args> struct sum<\/pre>\n\n\n\n
\u5b83\u662f\u524d\u5411\u58f0\u660e\uff0c\u58f0\u660e\u8fd9\u4e2asum\u7c7b\u662f\u4e00\u4e2a\u53ef\u53d8\u53c2\u6570\u6a21\u677f\u7c7b\uff1b\u7b2c\u4e8c\u90e8\u5206\u662f\u7c7b\u7684\u5b9a\u4e49\uff1a<\/p>\n\n\n\n
template<typename First, typename... Rest>\nstruct Sum<First, Rest...>\n{\n    enum { value = Sum<First>::value + Sum<Rest...>::value };\n};<\/pre>\n\n\n\n
\u5b83\u5b9a\u4e49\u4e86\u4e00\u4e2a\u90e8\u5206\u5c55\u5f00\u7684\u53ef\u53d8\u6a21\u53c2\u6570\u6a21\u677f\u7c7b\uff0c\u544a\u8bc9\u7f16\u8bd1\u5668\u5982\u4f55\u9012\u5f52\u5c55\u5f00\u53c2\u6570\u5305\u3002\u7b2c\u4e09\u90e8\u5206\u662f\u7279\u5316\u7684\u9012\u5f52\u7ec8\u6b62\u7c7b\uff1a<\/p>\n\n\n\n
template<typename Last> struct sum<last>\n{\n    enum { value = sizeof (First) };\n}<\/pre>\n\n\n\n
\u901a\u8fc7\u8fd9\u4e2a\u7279\u5316\u7684\u7c7b\u6765\u7ec8\u6b62\u9012\u5f52\uff1a<\/p>\n\n\n\n
template<typename First, typename... Args>struct sum;<\/pre>\n\n\n\n
\u8fd9\u4e2a\u524d\u5411\u58f0\u660e\u8981\u6c42sum\u7684\u6a21\u677f\u53c2\u6570\u81f3\u5c11\u6709\u4e00\u4e2a\uff0c\u56e0\u4e3a\u53ef\u53d8\u53c2\u6570\u6a21\u677f\u4e2d\u7684\u6a21\u677f\u53c2\u6570\u53ef\u4ee5\u67090\u4e2a\uff0c\u6709\u65f6\u50190\u4e2a\u6a21\u677f\u53c2\u6570\u6ca1\u6709\u610f\u4e49\uff0c\u5c31\u53ef\u4ee5\u901a\u8fc7\u4e0a\u9762\u7684\u58f0\u660e\u65b9\u5f0f\u6765\u9650\u5b9a\u6a21\u677f\u53c2\u6570\u4e0d\u80fd\u4e3a0\u4e2a\u3002\u4e0a\u9762\u7684\u8fd9\u79cd\u4e09\u6bb5\u5f0f\u7684\u5b9a\u4e49\u4e5f\u53ef\u4ee5\u6539\u4e3a\u4e24\u6bb5\u5f0f\u7684\uff0c\u53ef\u4ee5\u5c06\u524d\u5411\u58f0\u660e\u53bb\u6389\uff0c\u8fd9\u6837\u5b9a\u4e49\uff1a<\/p>\n\n\n\n
template<typename First, typename... Rest>\nstruct Sum\n{\n    enum { value = Sum<First>::value + Sum<Rest...>::value };\n};\n\ntemplate<typename Last>\nstruct Sum<Last>\n{\n    enum{ value = sizeof(Last) };\n};<\/pre>\n\n\n\n
\u4e0a\u9762\u7684\u65b9\u5f0f\u53ea\u8981\u4e00\u4e2a\u57fa\u672c\u7684\u6a21\u677f\u7c7b\u5b9a\u4e49\u548c\u4e00\u4e2a\u7279\u5316\u7684\u7ec8\u6b62\u51fd\u6570\u5c31\u884c\u4e86\uff0c\u800c\u4e14\u9650\u5b9a\u4e86\u6a21\u677f\u53c2\u6570\u81f3\u5c11\u6709\u4e00\u4e2a\u3002<\/p>\n\n\n\n
\u9012\u5f52\u7ec8\u6b62\u6a21\u677f\u7c7b\u53ef\u4ee5\u6709\u591a\u79cd\u5199\u6cd5\uff0c\u6bd4\u5982\u4e0a\u4f8b\u7684\u9012\u5f52\u7ec8\u6b62\u6a21\u677f\u7c7b\u8fd8\u53ef\u4ee5\u8fd9\u6837\u5199\uff1a<\/p>\n\n\n\n
template<typename... Args> struct sum;\ntemplate<typename First, typenameLast>\nstruct sum<First, Last>\n{ \n    enum{ value = sizeof(First) +sizeof(Last) };\n};<\/pre>\n\n\n\n
\u5728\u5c55\u5f00\u5230\u6700\u540e\u4e24\u4e2a\u53c2\u6570\u65f6\u7ec8\u6b62\u3002<\/p>\n\n\n\n
\u8fd8\u53ef\u4ee5\u5728\u5c55\u5f00\u52300\u4e2a\u53c2\u6570\u65f6\u7ec8\u6b62\uff1a<\/p>\n\n\n\n
template<>struct sum<> { enum{ value = 0 }; };<\/pre>\n\n\n\n
\u8fd8\u53ef\u4ee5\u4f7f\u7528std::integral_constant\u6765\u6d88\u9664\u679a\u4e3e\u5b9a\u4e49value\u3002\u5229\u7528std::integral_constant\u53ef\u4ee5\u83b7\u5f97\u7f16\u8bd1\u671f\u5e38\u91cf\u7684\u7279\u6027\uff0c\u53ef\u4ee5\u5c06\u524d\u9762\u7684sum\u4f8b\u5b50\u6539\u4e3a\u8fd9\u6837\uff1a<\/p>\n\n\n\n
\/\/\u524d\u5411\u58f0\u660e\ntemplate<typename First, typename... Args>\nstruct Sum;\n\n\/\/\u57fa\u672c\u5b9a\u4e49\ntemplate<typename First, typename... Rest>\nstruct Sum<First, Rest...> : std::integral_constant<int, Sum<First>::value + Sum<Rest...>::value>\n{\n};\n\n\/\/\u9012\u5f52\u7ec8\u6b62\ntemplate<typename Last>\nstruct Sum<Last> : std::integral_constant<int, sizeof(Last)>\n{\n};\nsum<int,double,short>::value;\/\/\u503c\u4e3a14<\/pre>\n\n\n\n
2.2.2\u7ee7\u627f\u65b9\u5f0f\u5c55\u5f00\u53c2\u6570\u5305<\/strong><\/h4>\n\n\n\n
\u8fd8\u53ef\u4ee5\u901a\u8fc7\u7ee7\u627f\u65b9\u5f0f\u6765\u5c55\u5f00\u53c2\u6570\u5305\uff0c\u6bd4\u5982\u4e0b\u9762\u7684\u4f8b\u5b50\u5c31\u662f\u901a\u8fc7\u7ee7\u627f\u7684\u65b9\u5f0f\u53bb\u5c55\u5f00\u53c2\u6570\u5305\uff1a<\/p>\n\n\n\n
\/\/\u6574\u578b\u5e8f\u5217\u7684\u5b9a\u4e49\ntemplate<int...>\nstruct IndexSeq{};\n\n\/\/\u7ee7\u627f\u65b9\u5f0f\uff0c\u5f00\u59cb\u5c55\u5f00\u53c2\u6570\u5305\ntemplate<int N, int... Indexes>\nstruct MakeIndexes : MakeIndexes<N - 1, N - 1, Indexes...> {};\n\n\/\/ \u6a21\u677f\u7279\u5316\uff0c\u7ec8\u6b62\u5c55\u5f00\u53c2\u6570\u5305\u7684\u6761\u4ef6\ntemplate<int... Indexes>\nstruct MakeIndexes<0, Indexes...>\n{\n    typedefIndexSeq<Indexes...> type;\n};\n\nint main()\n{\n    using T = MakeIndexes<3>::type;\n    cout <<typeid(T).name() << endl;\n    return 0;\n}<\/pre>\n\n\n\n
\u5176\u4e2dMakeIndexes\u7684\u4f5c\u7528\u662f\u4e3a\u4e86\u751f\u6210\u4e00\u4e2a\u53ef\u53d8\u53c2\u6570\u6a21\u677f\u7c7b\u7684\u6574\u6570\u5e8f\u5217\uff0c\u6700\u7ec8\u8f93\u51fa\u7684\u7c7b\u578b\u662f\uff1astruct IndexSeq<0,1,2>\u3002<\/p>\n\n\n\n
MakeIndexes\u7ee7\u627f\u4e8e\u81ea\u8eab\u7684\u4e00\u4e2a\u7279\u5316\u7684\u6a21\u677f\u7c7b\uff0c\u8fd9\u4e2a\u7279\u5316\u7684\u6a21\u677f\u7c7b\u540c\u65f6\u4e5f\u5728\u5c55\u5f00\u53c2\u6570\u5305\uff0c\u8fd9\u4e2a\u5c55\u5f00\u8fc7\u7a0b\u662f\u901a\u8fc7\u7ee7\u627f\u53d1\u8d77\u7684\uff0c\u76f4\u5230\u9047\u5230\u7279\u5316\u7684\u7ec8\u6b62\u6761\u4ef6\u5c55\u5f00\u8fc7\u7a0b\u624d\u7ed3\u675f\u3002MakeIndexes<1,2,3>::type\u7684\u5c55\u5f00\u8fc7\u7a0b\u662f\u8fd9\u6837\u7684\uff1a<\/p>\n\n\n\n
MakeIndexes<3> : MakeIndexes<2, 2>{}\nMakeIndexes<2, 2> : MakeIndexes<1, 1, 2>{}\nMakeIndexes<1, 1, 2> : MakeIndexes<0, 0, 1, 2>\n{\n    typedef IndexSeq<0, 1, 2> type;\n}<\/pre>\n\n\n\n
\u901a\u8fc7\u4e0d\u65ad\u7684\u7ee7\u627f\u9012\u5f52\u8c03\u7528\uff0c\u6700\u7ec8\u5f97\u5230\u6574\u578b\u5e8f\u5217IndexSeq<0, 1, 2>\u3002<\/p>\n\n\n\n
\u5982\u679c\u4e0d\u5e0c\u671b\u901a\u8fc7\u7ee7\u627f\u65b9\u5f0f\u53bb\u751f\u6210\u6574\u5f62\u5e8f\u5217\uff0c\u5219\u53ef\u4ee5\u901a\u8fc7\u4e0b\u9762\u7684\u65b9\u5f0f\u751f\u6210\u3002<\/p>\n\n\n\n
template<int N, int... Indexes>\nstruct MakeIndexes3\n{\n    using type = typename MakeIndexes3<N - 1, N - 1, Indexes...>::type;\n};\n\ntemplate<int... Indexes>\nstruct MakeIndexes3<0, Indexes...>\n{\n    typedef IndexSeq<Indexes...> type;\n};<\/pre>\n\n\n\n
\u6211\u4eec\u770b\u5230\u4e86\u5982\u4f55\u5229\u7528\u9012\u5f52\u4ee5\u53ca\u504f\u7279\u5316\u7b49\u65b9\u6cd5\u6765\u5c55\u5f00\u53ef\u53d8\u6a21\u7248\u53c2\u6570\uff0c\u90a3\u4e48\u5b9e\u9645\u5f53\u4e2d\u6211\u4eec\u4f1a\u600e\u4e48\u53bb\u4f7f\u7528\u5b83\u5462\uff1f\u6211\u4eec\u53ef\u4ee5\u7528\u53ef\u53d8\u6a21\u7248\u53c2\u6570\u6765\u6d88\u9664\u4e00\u4e9b\u91cd\u590d\u7684\u4ee3\u7801\u4ee5\u53ca\u5b9e\u73b0\u4e00\u4e9b\u9ad8\u7ea7\u529f\u80fd\uff0c\u4e0b\u9762\u6211\u4eec\u6765\u770b\u770b\u53ef\u53d8\u6a21\u7248\u53c2\u6570\u7684\u4e00\u4e9b\u5e94\u7528\u3002<\/p>\n\n\n\n
3\u53ef\u53d8\u53c2\u6570\u6a21\u7248\u6d88\u9664\u91cd\u590d\u4ee3\u7801<\/strong><\/h2>\n\n\n\n
C++11\u4e4b\u524d\u5982\u679c\u8981\u5199\u4e00\u4e2a\u6cdb\u5316\u7684\u5de5\u5382\u51fd\u6570\uff0c\u8fd9\u4e2a\u5de5\u5382\u51fd\u6570\u80fd\u63a5\u53d7\u4efb\u610f\u7c7b\u578b\u7684\u5165\u53c2\uff0c\u5e76\u4e14\u53c2\u6570\u4e2a\u6570\u8981\u80fd\u6ee1\u8db3\u5927\u90e8\u5206\u7684\u5e94\u7528\u9700\u6c42\u7684\u8bdd\uff0c\u6211\u4eec\u4e0d\u5f97\u4e0d\u5b9a\u4e49\u5f88\u591a\u91cd\u590d\u7684\u6a21\u7248\u5b9a\u4e49\uff0c\u6bd4\u5982\u4e0b\u9762\u7684\u4ee3\u7801\uff1a<\/p>\n\n\n\n
template<typename T>\nT* Instance()\n{\n    return new T();\n}\n\ntemplate<typename T, typename T0>\nT* Instance(T0 arg0)\n{\n    return new T(arg0);\n}\n\ntemplate<typename T, typename T0, typename T1>\nT* Instance(T0 arg0, T1 arg1)\n{\n    return new T(arg0, arg1);\n}\n\ntemplate<typename T, typename T0, typename T1, typename T2>\nT* Instance(T0 arg0, T1 arg1, T2 arg2)\n{\n    return new T(arg0, arg1, arg2);\n}\n\ntemplate<typename T, typename T0, typename T1, typename T2, typename T3>\nT* Instance(T0 arg0, T1 arg1, T2 arg2, T3 arg3)\n{\n    return new T(arg0, arg1, arg2, arg3);\n}\n\ntemplate<typename T, typename T0, typename T1, typename T2, typename T3, typename T4>\nT* Instance(T0 arg0, T1 arg1, T2 arg2, T3 arg3, T4 arg4)\n{\n    return new T(arg0, arg1, arg2, arg3, arg4);\n}\nstruct A\n{\n    A(int){}\n};\n\nstruct B\n{\n    B(int,double){}\n};\nA* pa = Instance<A>(1);\nB* pb = Instance<B>(1,2);<\/pre>\n\n\n\n
\u53ef\u4ee5\u770b\u5230\u8fd9\u4e2a\u6cdb\u578b\u5de5\u5382\u51fd\u6570\u5b58\u5728\u5927\u91cf\u7684\u91cd\u590d\u7684\u6a21\u677f\u5b9a\u4e49\uff0c\u5e76\u4e14\u9650\u5b9a\u4e86\u6a21\u677f\u53c2\u6570\u3002\u7528\u53ef\u53d8\u6a21\u677f\u53c2\u6570\u53ef\u4ee5\u6d88\u9664\u91cd\u590d\uff0c\u540c\u65f6\u53bb\u6389\u53c2\u6570\u4e2a\u6570\u7684\u9650\u5236\uff0c\u4ee3\u7801\u5f88\u7b80\u6d01\uff0c \u901a\u8fc7\u53ef\u53d8\u53c2\u6570\u6a21\u7248\u4f18\u5316\u540e\u7684\u5de5\u5382\u51fd\u6570\u5982\u4e0b\uff1a<\/p>\n\n\n\n
template<typename\u2026  Args>\nT* Instance(Args&&\u2026 args)\n{\n    return new T(std::forward<Args>(args)\u2026);\n}\nA* pa = Instance<A>(1);\nB* pb = Instance<B>(1,2);<\/pre>\n\n\n\n
4\u53ef\u53d8\u53c2\u6570\u6a21\u7248\u5b9e\u73b0\u6cdb\u5316\u7684delegate<\/strong><\/h2>\n\n\n\n
C++\u4e2d\u6ca1\u6709\u7c7b\u4f3cC#\u7684\u59d4\u6258\uff0c\u6211\u4eec\u53ef\u4ee5\u501f\u52a9\u53ef\u53d8\u6a21\u7248\u53c2\u6570\u6765\u5b9e\u73b0\u4e00\u4e2a\u3002C#\u4e2d\u7684\u59d4\u6258\u7684\u57fa\u672c\u7528\u6cd5\u662f\u8fd9\u6837\u7684\uff1a<\/p>\n\n\n\n
delegate int AggregateDelegate(int x, int y);\/\/\u58f0\u660e\u59d4\u6258\u7c7b\u578b\n\nint Add(int x, int y){return x+y;}\nint Sub(int x, int y){return x-y;}\n\nAggregateDelegate add = Add;\nadd(1,2);\/\/\u8c03\u7528\u59d4\u6258\u5bf9\u8c61\u6c42\u548c\nAggregateDelegate sub = Sub;\nsub(2,1);\/\/ \u8c03\u7528\u59d4\u6258\u5bf9\u8c61\u76f8\u51cf<\/pre>\n\n\n\n
C#\u4e2d\u7684\u59d4\u6258\u7684\u4f7f\u7528\u9700\u8981\u5148\u5b9a\u4e49\u4e00\u4e2a\u59d4\u6258\u7c7b\u578b\uff0c\u8fd9\u4e2a\u59d4\u6258\u7c7b\u578b\u4e0d\u80fd\u6cdb\u5316\uff0c\u5373\u59d4\u6258\u7c7b\u578b\u4e00\u65e6\u58f0\u660e\u4e4b\u540e\u5c31\u4e0d\u80fd\u518d\u7528\u6765\u63a5\u53d7\u5176\u5b83\u7c7b\u578b\u7684\u51fd\u6570\u4e86\uff0c\u6bd4\u5982\u8fd9\u6837\u7528\uff1a<\/p>\n\n\n\n
int Fun(int x, int y, int z){return x+y+z;}\nint Fun1(string s, string r){return s.Length+r.Length; }\nAggregateDelegate fun = Fun; \/\/\u7f16\u8bd1\u62a5\u9519\uff0c\u53ea\u80fd\u8d4b\u503c\u76f8\u540c\u7c7b\u578b\u7684\u51fd\u6570\nAggregateDelegate fun1 = Fun1;\/\/\u7f16\u8bd1\u62a5\u9519\uff0c\u53c2\u6570\u7c7b\u578b\u4e0d\u5339\u914d<\/pre>\n\n\n\n
\u8fd9\u91cc\u4e0d\u80fd\u6cdb\u5316\u7684\u539f\u56e0\u662f\u58f0\u660e\u59d4\u6258\u7c7b\u578b\u7684\u65f6\u5019\u5c31\u9650\u5b9a\u4e86\u53c2\u6570\u7c7b\u578b\u548c\u4e2a\u6570\uff0c\u5728C++11\u91cc\u4e0d\u5b58\u5728\u8fd9\u4e2a\u95ee\u9898\u4e86\uff0c\u56e0\u4e3a\u6709\u4e86\u53ef\u53d8\u6a21\u7248\u53c2\u6570\uff0c\u5b83\u5c31\u4ee3\u8868\u4e86\u4efb\u610f\u7c7b\u578b\u548c\u4e2a\u6570\u7684\u53c2\u6570\u4e86\uff0c\u4e0b\u9762\u8ba9\u6211\u4eec\u6765\u770b\u4e00\u4e0b\u5982\u4f55\u5b9e\u73b0\u4e00\u4e2a\u529f\u80fd\u66f4\u52a0\u6cdb\u5316\u7684C++\u7248\u672c\u7684\u59d4\u6258\uff08\u8fd9\u91cc\u4e3a\u4e86\u7b80\u5355\u8d77\u89c1\u53ea\u5904\u7406\u6210\u5458\u51fd\u6570\u7684\u60c5\u51b5\uff0c\u5e76\u4e14\u5ffd\u7565const\u3001volatile\u548cconst volatile\u6210\u5458\u51fd\u6570\u7684\u5904\u7406\uff09\u3002<\/p>\n\n\n\n
template <class T, class R, typename... Args>\nclass  MyDelegate\n{\npublic:\n    MyDelegate(T* t, R  (T::*f)(Args...) ):m_t(t),m_f(f) {}\n\n    R operator()(Args&&... args) \n    {\n            return (m_t->*m_f)(std::forward<Args>(args) ...);\n    }\n\nprivate:\n    T* m_t;\n    R  (T::*m_f)(Args...);\n};   \n\ntemplate <class T, class R, typename... Args>\nMyDelegate<T, R, Args...> CreateDelegate(T* t, R (T::*f)(Args...))\n{\n    return MyDelegate<T, R, Args...>(t, f);\n}\n\nstruct A\n{\n    void Fun(int i){cout<<i<<endl;}\n    void Fun1(int i, double j){cout<<i+j<<endl;}\n};\n\nint main()\n{\n    A a;\n    auto d = CreateDelegate(&a, &A::Fun); \/\/\u521b\u5efa\u59d4\u6258\n    d(1); \/\/\u8c03\u7528\u59d4\u6258\uff0c\u5c06\u8f93\u51fa1\n    auto d1 = CreateDelegate(&a, &A::Fun1); \/\/\u521b\u5efa\u59d4\u6258\n    d1(1, 2.5); \/\/\u8c03\u7528\u59d4\u6258\uff0c\u5c06\u8f93\u51fa3.5\n}<\/pre>\n\n\n\n
MyDelegate\u5b9e\u73b0\u7684\u5173\u952e\u662f\u5185\u90e8\u5b9a\u4e49\u4e86\u4e00\u4e2a\u80fd\u63a5\u53d7\u4efb\u610f\u7c7b\u578b\u548c\u4e2a\u6570\u53c2\u6570\u7684\u201c\u4e07\u80fd\u51fd\u6570\u201d\uff1aR  (T::*m_f)(Args…)\uff0c\u6b63\u662f\u7531\u4e8e\u53ef\u53d8\u6a21\u7248\u53c2\u6570\u7684\u7279\u6027\uff0c\u6240\u4ee5\u6211\u4eec\u624d\u80fd\u591f\u8ba9\u8fd9\u4e2am_f\u63a5\u53d7\u4efb\u610f\u53c2\u6570\u3002<\/p>\n\n\n\n
5\u603b\u7ed3<\/strong><\/h2>\n\n\n\n
\u4f7f\u7528\u53ef\u53d8\u6a21\u7248\u53c2\u6570\u7684\u8fd9\u4e9b\u6280\u5de7\u76f8\u4fe1\u8bfb\u8005\u770b\u4e86\u4f1a\u6709\u8033\u76ee\u4e00\u65b0\u4e4b\u611f\uff0c\u4f7f\u7528\u53ef\u53d8\u6a21\u7248\u53c2\u6570\u7684\u5173\u952e\u662f\u5982\u4f55\u5c55\u5f00\u53c2\u6570\u5305\uff0c\u5c55\u5f00\u53c2\u6570\u5305\u7684\u8fc7\u7a0b\u662f\u5f88\u7cbe\u5999\u7684\uff0c\u4f53\u73b0\u4e86\u6cdb\u5316\u4e4b\u7f8e\u3001\u9012\u5f52\u4e4b\u7f8e\uff0c\u6b63\u662f\u56e0\u4e3a\u5b83\u5177\u6709\u795e\u5947\u7684\u201c\u9b54\u529b\u201d\uff0c\u6240\u4ee5\u6211\u4eec\u53ef\u4ee5\u66f4\u6cdb\u5316\u7684\u53bb\u5904\u7406\u95ee\u9898\uff0c\u6bd4\u5982\u7528\u5b83\u6765\u6d88\u9664\u91cd\u590d\u7684\u6a21\u7248\u5b9a\u4e49\uff0c\u7528\u5b83\u6765\u5b9a\u4e49\u4e00\u4e2a\u80fd\u63a5\u53d7\u4efb\u610f\u53c2\u6570\u7684\u201c\u4e07\u80fd\u51fd\u6570\u201d\u7b49\u3002\u5176\u5b9e\uff0c\u53ef\u53d8\u6a21\u7248\u53c2\u6570\u7684\u4f5c\u7528\u8fdc\u4e0d\u6b62\u6587\u4e2d\u5217\u4e3e\u7684\u90a3\u4e9b\u4f5c\u7528\uff0c\u5b83\u8fd8\u53ef\u4ee5\u548c\u5176\u5b83C++11\u7279\u6027\u7ed3\u5408\u8d77\u6765\uff0c\u6bd4\u5982type_traits\u3001std::tuple\u7b49\u7279\u6027\uff0c\u53d1\u6325\u66f4\u52a0\u5f3a\u5927\u7684\u5a01\u529b\uff0c\u5c06\u5728\u540e\u9762\u6a21\u677f\u5143\u7f16\u7a0b\u7684\u5e94\u7528\u4e2d\u4ecb\u7ecd\u3002<\/p>\n\n\n\n
https:\/\/www.cnblogs.com\/qicosmos\/p\/4325949.html<\/a>
https:\/\/blog.csdn.net\/weixin_40539125\/article\/details\/90245358
https:\/\/en.cppreference.com\/w\/cpp\/language\/parameter_pack<\/p>\n","protected":false},"excerpt":{"rendered":"
1\u6982\u8ff0 C++11\u7684\u65b0\u7279\u6027–\u53ef\u53d8\u6a21\u7248\u53c2\u6570\uff08variadic templates\uff09\u662fC++ […]<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"closed","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[28],"tags":[],"_links":{"self":[{"href":"https:\/\/blog.coolcoding.cn\/index.php?rest_route=\/wp\/v2\/posts\/2964"}],"collection":[{"href":"https:\/\/blog.coolcoding.cn\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/blog.coolcoding.cn\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/blog.coolcoding.cn\/index.php?rest_route=\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/blog.coolcoding.cn\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=2964"}],"version-history":[{"count":2,"href":"https:\/\/blog.coolcoding.cn\/index.php?rest_route=\/wp\/v2\/posts\/2964\/revisions"}],"predecessor-version":[{"id":2966,"href":"https:\/\/blog.coolcoding.cn\/index.php?rest_route=\/wp\/v2\/posts\/2964\/revisions\/2966"}],"wp:attachment":[{"href":"https:\/\/blog.coolcoding.cn\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=2964"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/blog.coolcoding.cn\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=2964"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/blog.coolcoding.cn\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=2964"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}