[{"data":1,"prerenderedAt":232},["ShallowReactive",2],{"tag-闭包-1":3},{"title":4,"articles":5,"hot_article":17,"month_arch":80,"total":228,"cover":229},"闭包 - 独孤影的博客",[6],{"id":7,"title":8,"uri":9,"author":10,"tags":11,"created_at":14,"view_count":15,"content":16},74,"初学rust，闭包引用外部变量","closure-can-not-use-var-outsite-the-closure-function","duguying",[12,13],"rust","闭包","2022-09-27 22:44:09",406,"\u003Cp>今天又遇到一个新的问题，那就是在闭包函数中，无法引用闭包函数之外的变量。\u003C\u002Fp>\n\n\u003Cpre style=\"color:#e6edf3;background-color:#0d1117;white-space:pre-wrap;word-break:break-word;\">\u003Ccode>\u003Cspan style=\"display:flex;\">\u003Cspan>\u003Cspan style=\"color:#ff7b72\">fn\u003C\u002Fspan> \u003Cspan style=\"color:#d2a8ff;font-weight:bold\">main\u003C\u002Fspan>()\u003Cspan style=\"color:#6e7681\"> \u003C\u002Fspan>{\u003Cspan style=\"color:#6e7681\">\n\u003C\u002Fspan>\u003C\u002Fspan>\u003C\u002Fspan>\u003Cspan style=\"display:flex;\">\u003Cspan>\u003Cspan style=\"color:#6e7681\">\u003C\u002Fspan>\u003Cspan style=\"color:#6e7681\">    \u003C\u002Fspan>\u003Cspan style=\"color:#ff7b72\">let\u003C\u002Fspan>\u003Cspan style=\"color:#6e7681\"> \u003C\u002Fspan>cfg\u003Cspan style=\"color:#6e7681\"> \u003C\u002Fspan>\u003Cspan style=\"color:#ff7b72;font-weight:bold\">=\u003C\u002Fspan>\u003Cspan style=\"color:#6e7681\"> \u003C\u002Fspan>config::cfg::get_config();\u003Cspan style=\"color:#6e7681\">\n\u003C\u002Fspan>\u003C\u002Fspan>\u003C\u002Fspan>\u003Cspan style=\"display:flex;\">\u003Cspan>\u003Cspan style=\"color:#6e7681\">\u003C\u002Fspan>\u003Cspan style=\"color:#6e7681\">    \u003C\u002Fspan>\u003Cspan style=\"color:#ff7b72\">let\u003C\u002Fspan>\u003Cspan style=\"color:#6e7681\"> \u003C\u002Fspan>filename\u003Cspan style=\"color:#6e7681\"> \u003C\u002Fspan>\u003Cspan style=\"color:#ff7b72;font-weight:bold\">=\u003C\u002Fspan>\u003Cspan style=\"color:#6e7681\"> \u003C\u002Fspan>cfg.las.as_ref().unwrap().access_log.as_ref().unwrap();\u003Cspan style=\"color:#6e7681\">\n\u003C\u002Fspan>\u003C\u002Fspan>\u003C\u002Fspan>\u003Cspan style=\"display:flex;\">\u003Cspan>\u003Cspan style=\"color:#6e7681\">\u003C\u002Fspan>\u003Cspan style=\"color:#6e7681\">    \u003C\u002Fspan>\u003Cspan style=\"color:#8b949e;font-style:italic\">\u002F\u002F println!("{}",filename);\n\u003C\u002Fspan>\u003C\u002Fspan>\u003C\u002Fspan>\u003Cspan style=\"display:flex;\">\u003Cspan>\u003Cspan style=\"color:#8b949e;font-style:italic\">\u003C\u002Fspan>\u003Cspan style=\"color:#6e7681\">    \u003C\u002Fspan>\u003Cspan style=\"color:#8b949e;font-style:italic\">\u002F\u002F let mut p = poly::Poly::new();\n\u003C\u002Fspan>\u003C\u002Fspan>\u003C\u002Fspan>\u003Cspan style=\"display:flex;\">\u003Cspan>\u003Cspan style=\"color:#8b949e;font-style:italic\">\u003C\u002Fspan>\u003Cspan style=\"color:#6e7681\">    \u003C\u002Fspan>\u003Cspan style=\"color:#ff7b72\">let\u003C\u002Fspan>\u003Cspan style=\"color:#6e7681\"> \u003C\u002Fspan>\u003Cspan style=\"color:#ff7b72\">mut\u003C\u002Fspan>\u003Cspan style=\"color:#6e7681\"> \u003C\u002Fspan>s\u003Cspan style=\"color:#6e7681\"> \u003C\u002Fspan>\u003Cspan style=\"color:#ff7b72;font-weight:bold\">=\u003C\u002Fspan>\u003Cspan style=\"color:#6e7681\"> \u003C\u002Fspan>String::from(\u003Cspan style=\"color:#a5d6ff\">"\u003C\u002Fspan>\u003Cspan style=\"color:#a5d6ff\">_\u003C\u002Fspan>\u003Cspan style=\"color:#a5d6ff\">"\u003C\u002Fspan>);\u003Cspan style=\"color:#6e7681\">\n\u003C\u002Fspan>\u003C\u002Fspan>\u003C\u002Fspan>\u003Cspan style=\"display:flex;\">\u003Cspan>\u003Cspan style=\"color:#6e7681\">\u003C\u002Fspan>\u003Cspan style=\"color:#6e7681\">    \u003C\u002Fspan>\u003Cspan style=\"color:#ff7b72\">let\u003C\u002Fspan>\u003Cspan style=\"color:#6e7681\"> \u003C\u002Fspan>\u003Cspan style=\"color:#ff7b72\">mut\u003C\u002Fspan>\u003Cspan style=\"color:#6e7681\"> \u003C\u002Fspan>log_watcher\u003Cspan style=\"color:#6e7681\"> \u003C\u002Fspan>\u003Cspan style=\"color:#ff7b72;font-weight:bold\">=\u003C\u002Fspan>\u003Cspan style=\"color:#6e7681\"> \u003C\u002Fspan>LogWatcher::register(filename.to_string()).unwrap();\u003Cspan style=\"color:#6e7681\">\n\u003C\u002Fspan>\u003C\u002Fspan>\u003C\u002Fspan>\u003Cspan style=\"display:flex;\">\u003Cspan>\u003Cspan style=\"color:#6e7681\">\u003C\u002Fspan>\u003Cspan style=\"color:#6e7681\">\n\u003C\u002Fspan>\u003C\u002Fspan>\u003C\u002Fspan>\u003Cspan style=\"display:flex;\">\u003Cspan>\u003Cspan style=\"color:#6e7681\">\u003C\u002Fspan>\u003Cspan style=\"color:#6e7681\">    \u003C\u002Fspan>log_watcher.watch(\u003Cspan style=\"color:#ff7b72;font-weight:bold\">|\u003C\u002Fspan>line: String\u003Cspan style=\"color:#ff7b72;font-weight:bold\">|\u003C\u002Fspan>\u003Cspan style=\"color:#6e7681\"> \u003C\u002Fspan>{\u003Cspan style=\"color:#6e7681\">\n\u003C\u002Fspan>\u003C\u002Fspan>\u003C\u002Fspan>\u003Cspan style=\"display:flex;\">\u003Cspan>\u003Cspan style=\"color:#6e7681\">\u003C\u002Fspan>\u003Cspan style=\"color:#6e7681\">        \u003C\u002Fspan>\u003Cspan style=\"color:#ff7b72\">let\u003C\u002Fspan>\u003Cspan style=\"color:#6e7681\"> \u003C\u002Fspan>(_,\u003Cspan style=\"color:#6e7681\"> \u003C\u002Fspan>token)\u003Cspan style=\"color:#6e7681\"> \u003C\u002Fspan>\u003Cspan style=\"color:#ff7b72;font-weight:bold\">=\u003C\u002Fspan>\u003Cspan style=\"color:#6e7681\"> \u003C\u002Fspan>parse::lex::parser(\u003Cspan style=\"color:#ff7b72;font-weight:bold\">&\u003C\u002Fspan>line);\u003Cspan style=\"color:#6e7681\">\n\u003C\u002Fspan>\u003C\u002Fspan>\u003C\u002Fspan>\u003Cspan style=\"display:flex;\">\u003Cspan>\u003Cspan style=\"color:#6e7681\">\u003C\u002Fspan>\u003Cspan style=\"color:#6e7681\">        \u003C\u002Fspan>\u003Cspan style=\"color:#8b949e;font-style:italic\">\u002F\u002F p.push(LineStat {});\n\u003C\u002Fspan>\u003C\u002Fspan>\u003C\u002Fspan>\u003Cspan style=\"display:flex;\">\u003Cspan>\u003Cspan style=\"color:#8b949e;font-style:italic\">\u003C\u002Fspan>\u003Cspan style=\"color:#6e7681\">        \u003C\u002Fspan>print!\u003Cspan style=\"color:#6e7681\">\u003C\u002Fspan>(\u003Cspan style=\"color:#6e7681\">\u003C\u002Fspan>\u003Cspan style=\"color:#a5d6ff\">"\u003C\u002Fspan>\u003Cspan style=\"color:#a5d6ff\">{}\u003C\u002Fspan>\u003Cspan style=\"color:#a5d6ff\">"\u003C\u002Fspan>,\u003Cspan style=\"color:#6e7681\"> \u003C\u002Fspan>s);\u003Cspan style=\"color:#6e7681\">\n\u003C\u002Fspan>\u003C\u002Fspan>\u003C\u002Fspan>\u003Cspan style=\"display:flex;\">\u003Cspan>\u003Cspan style=\"color:#6e7681\">\u003C\u002Fspan>\u003Cspan style=\"color:#6e7681\">        \u003C\u002Fspan>process::report::send(token);\u003Cspan style=\"color:#6e7681\">\n\u003C\u002Fspan>\u003C\u002Fspan>\u003C\u002Fspan>\u003Cspan style=\"display:flex;\">\u003Cspan>\u003Cspan style=\"color:#6e7681\">\u003C\u002Fspan>\u003Cspan style=\"color:#6e7681\">    \u003C\u002Fspan>});\u003Cspan style=\"color:#6e7681\">\n\u003C\u002Fspan>\u003C\u002Fspan>\u003C\u002Fspan>\u003Cspan style=\"display:flex;\">\u003Cspan>\u003Cspan style=\"color:#6e7681\">\u003C\u002Fspan>}\u003Cspan style=\"color:#6e7681\">\n\u003C\u002Fspan>\u003C\u002Fspan>\u003C\u002Fspan>\u003C\u002Fcode>\u003C\u002Fpre>\n\n\u003Cp>上面代码中，\u003Ccode class=\"inline-code\">watch\u003C\u002Fcode>传入参数为一个闭包函数，其中需要引用\u003Ccode class=\"inline-code\">main\u003C\u002Fcode>函数中的局部变量\u003Ccode class=\"inline-code\">s\u003C\u002Fcode>，但是会报错\u003C\u002Fp>\n\n\u003Cpre style=\"color:#e6edf3;background-color:#0d1117;white-space:pre-wrap;word-break:break-word;\">\u003Ccode>\u003Cspan style=\"display:flex;\">\u003Cspan>error[E0308]: mismatched types\n\u003C\u002Fspan>\u003C\u002Fspan>\u003Cspan style=\"display:flex;\">\u003Cspan>  --> src\u002Fmain.rs:22:23\n\u003C\u002Fspan>\u003C\u002Fspan>\u003Cspan style=\"display:flex;\">\u003Cspan>   |\n\u003C\u002Fspan>\u003C\u002Fspan>\u003Cspan style=\"display:flex;\">\u003Cspan>22 |       log_watcher.watch(|line: String| {\n\u003C\u002Fspan>\u003C\u002Fspan>\u003Cspan style=\"display:flex;\">\u003Cspan>   |  _______________________^\n\u003C\u002Fspan>\u003C\u002Fspan>\u003Cspan style=\"display:flex;\">\u003Cspan>23 | |         let (_, token) = parse::lex::parser(&line);\n\u003C\u002Fspan>\u003C\u002Fspan>\u003Cspan style=\"display:flex;\">\u003Cspan>24 | |         \u002F\u002F p.push(LineStat {});\n\u003C\u002Fspan>\u003C\u002Fspan>\u003Cspan style=\"display:flex;\">\u003Cspan>25 | |         print!("{}", s);\n\u003C\u002Fspan>\u003C\u002Fspan>\u003Cspan style=\"display:flex;\">\u003Cspan>26 | |         process::report::send(token);\n\u003C\u002Fspan>\u003C\u002Fspan>\u003Cspan style=\"display:flex;\">\u003Cspan>27 | |     });\n\u003C\u002Fspan>\u003C\u002Fspan>\u003Cspan style=\"display:flex;\">\u003Cspan>   | |_____^ expected fn pointer, found closure\n\u003C\u002Fspan>\u003C\u002Fspan>\u003Cspan style=\"display:flex;\">\u003Cspan>   |\n\u003C\u002Fspan>\u003C\u002Fspan>\u003Cspan style=\"display:flex;\">\u003Cspan>   = note: expected fn pointer `fn(std::string::String)`\n\u003C\u002Fspan>\u003C\u002Fspan>\u003Cspan style=\"display:flex;\">\u003Cspan>                 found closure `[closure@src\u002Fmain.rs:22:23: 27:6]`\n\u003C\u002Fspan>\u003C\u002Fspan>\u003Cspan style=\"display:flex;\">\u003Cspan>note: closures can only be coerced to `fn` types if they do not capture any variables\n\u003C\u002Fspan>\u003C\u002Fspan>\u003C\u002Fcode>\u003C\u002Fpre>\n\n\u003Cp>查看\u003Ccode class=\"inline-code\">logwatcher\u003C\u002Fcode>源码，\u003Ccode class=\"inline-code\">watch\u003C\u002Fcode>该版本(0.1.0)方法定义如下\u003C\u002Fp>\n\n\u003Cpre style=\"color:#e6edf3;background-color:#0d1117;white-space:pre-wrap;word-break:break-word;\">\u003Ccode>\u003Cspan style=\"display:flex;\">\u003Cspan>\u003Cspan style=\"color:#ff7b72\">pub\u003C\u002Fspan>\u003Cspan style=\"color:#6e7681\"> \u003C\u002Fspan>\u003Cspan style=\"color:#ff7b72\">fn\u003C\u002Fspan> \u003Cspan style=\"color:#d2a8ff;font-weight:bold\">watch\u003C\u002Fspan>(\u003Cspan style=\"color:#ff7b72;font-weight:bold\">&\u003C\u002Fspan>\u003Cspan style=\"color:#ff7b72\">mut\u003C\u002Fspan>\u003Cspan style=\"color:#6e7681\"> \u003C\u002Fspan>self,\u003Cspan style=\"color:#6e7681\"> \u003C\u002Fspan>callback: \u003Cspan style=\"color:#f0883e;font-weight:bold\">fn\u003C\u002Fspan>\u003Cspan style=\"color:#6e7681\"> \u003C\u002Fspan>(line: String))\u003Cspan style=\"color:#6e7681\"> \u003C\u002Fspan>{\u003Cspan style=\"color:#6e7681\">\n\u003C\u002Fspan>\u003C\u002Fspan>\u003C\u002Fspan>\u003Cspan style=\"display:flex;\">\u003Cspan>\u003Cspan style=\"color:#6e7681\">\u003C\u002Fspan>\u003Cspan style=\"color:#6e7681\">    \u003C\u002Fspan>\u003Cspan style=\"color:#ff7b72;font-weight:bold\">..\u003C\u002Fspan>\u003Cspan style=\"color:#ff7b72;font-weight:bold\">..\u003C\u002Fspan>\u003Cspan style=\"color:#6e7681\">\n\u003C\u002Fspan>\u003C\u002Fspan>\u003C\u002Fspan>\u003Cspan style=\"display:flex;\">\u003Cspan>\u003Cspan style=\"color:#6e7681\">\u003C\u002Fspan>}\u003Cspan style=\"color:#6e7681\">\n\u003C\u002Fspan>\u003C\u002Fspan>\u003C\u002Fspan>\u003C\u002Fcode>\u003C\u002Fpre>\n\n\u003Cp>不过我后来发现\u003Ccode class=\"inline-code\">logwatcher\u003C\u002Fcode>版本升级到(0.1.1)之后，该方法变为\u003C\u002Fp>\n\n\u003Cpre style=\"color:#e6edf3;background-color:#0d1117;white-space:pre-wrap;word-break:break-word;\">\u003Ccode>\u003Cspan style=\"display:flex;\">\u003Cspan>\u003Cspan style=\"color:#ff7b72\">pub\u003C\u002Fspan>\u003Cspan style=\"color:#6e7681\"> \u003C\u002Fspan>\u003Cspan style=\"color:#ff7b72\">fn\u003C\u002Fspan> \u003Cspan style=\"color:#d2a8ff;font-weight:bold\">watch\u003C\u002Fspan>\u003Cspan style=\"color:#ff7b72;font-weight:bold\"><\u003C\u002Fspan>F: \u003Cspan style=\"color:#ff7b72;font-weight:bold\">?\u003C\u002Fspan>Sized\u003Cspan style=\"color:#ff7b72;font-weight:bold\">>\u003C\u002Fspan>(\u003Cspan style=\"color:#ff7b72;font-weight:bold\">&\u003C\u002Fspan>\u003Cspan style=\"color:#ff7b72\">mut\u003C\u002Fspan>\u003Cspan style=\"color:#6e7681\"> \u003C\u002Fspan>self,\u003Cspan style=\"color:#6e7681\"> \u003C\u002Fspan>callback: \u003Cspan style=\"color:#79c0ff\">&\u003C\u002Fspan>\u003Cspan style=\"color:#f0883e;font-weight:bold\">mut\u003C\u002Fspan>\u003Cspan style=\"color:#6e7681\"> \u003C\u002Fspan>F)\u003Cspan style=\"color:#6e7681\">\n\u003C\u002Fspan>\u003C\u002Fspan>\u003C\u002Fspan>\u003Cspan style=\"display:flex;\">\u003Cspan>\u003Cspan style=\"color:#6e7681\">\u003C\u002Fspan>\u003Cspan style=\"color:#ff7b72\">where\u003C\u002Fspan>\u003Cspan style=\"color:#6e7681\">\n\u003C\u002Fspan>\u003C\u002Fspan>\u003C\u002Fspan>\u003Cspan style=\"display:flex;\">\u003Cspan>\u003Cspan style=\"color:#6e7681\">\u003C\u002Fspan>\u003Cspan style=\"color:#6e7681\">    \u003C\u002Fspan>F: FnMut(String)\u003Cspan style=\"color:#6e7681\"> \u003C\u002Fspan>-> \u003Cspan style=\"color:#f0883e;font-weight:bold\">LogWatcherAction\u003C\u002Fspan>,\u003Cspan style=\"color:#6e7681\">\n\u003C\u002Fspan>\u003C\u002Fspan>\u003C\u002Fspan>\u003Cspan style=\"display:flex;\">\u003Cspan>\u003Cspan style=\"color:#6e7681\">\u003C\u002Fspan>{\u003Cspan style=\"color:#6e7681\">\n\u003C\u002Fspan>\u003C\u002Fspan>\u003C\u002Fspan>\u003Cspan style=\"display:flex;\">\u003Cspan>\u003Cspan style=\"color:#6e7681\">\u003C\u002Fspan>\u003Cspan style=\"color:#6e7681\">    \u003C\u002Fspan>\u003Cspan style=\"color:#ff7b72;font-weight:bold\">..\u003C\u002Fspan>\u003Cspan style=\"color:#ff7b72;font-weight:bold\">..\u003C\u002Fspan>\u003Cspan style=\"color:#6e7681\">\n\u003C\u002Fspan>\u003C\u002Fspan>\u003C\u002Fspan>\u003Cspan style=\"display:flex;\">\u003Cspan>\u003Cspan style=\"color:#6e7681\">\u003C\u002Fspan>}\u003Cspan style=\"color:#6e7681\">\n\u003C\u002Fspan>\u003C\u002Fspan>\u003C\u002Fspan>\u003C\u002Fcode>\u003C\u002Fpre>\n\n\u003Cp>如此可以正常调用，代码如下\u003C\u002Fp>\n\n\u003Cpre style=\"color:#e6edf3;background-color:#0d1117;white-space:pre-wrap;word-break:break-word;\">\u003Ccode>\u003Cspan style=\"display:flex;\">\u003Cspan>\u003Cspan style=\"color:#ff7b72\">fn\u003C\u002Fspan> \u003Cspan style=\"color:#d2a8ff;font-weight:bold\">main\u003C\u002Fspan>()\u003Cspan style=\"color:#6e7681\"> \u003C\u002Fspan>{\u003Cspan style=\"color:#6e7681\">\n\u003C\u002Fspan>\u003C\u002Fspan>\u003C\u002Fspan>\u003Cspan style=\"display:flex;\">\u003Cspan>\u003Cspan style=\"color:#6e7681\">\u003C\u002Fspan>\u003Cspan style=\"color:#6e7681\">    \u003C\u002Fspan>\u003Cspan style=\"color:#ff7b72\">let\u003C\u002Fspan>\u003Cspan style=\"color:#6e7681\"> \u003C\u002Fspan>cfg\u003Cspan style=\"color:#6e7681\"> \u003C\u002Fspan>\u003Cspan style=\"color:#ff7b72;font-weight:bold\">=\u003C\u002Fspan>\u003Cspan style=\"color:#6e7681\"> \u003C\u002Fspan>config::cfg::get_config();\u003Cspan style=\"color:#6e7681\">\n\u003C\u002Fspan>\u003C\u002Fspan>\u003C\u002Fspan>\u003Cspan style=\"display:flex;\">\u003Cspan>\u003Cspan style=\"color:#6e7681\">\u003C\u002Fspan>\u003Cspan style=\"color:#6e7681\">    \u003C\u002Fspan>\u003Cspan style=\"color:#ff7b72\">let\u003C\u002Fspan>\u003Cspan style=\"color:#6e7681\"> \u003C\u002Fspan>filename\u003Cspan style=\"color:#6e7681\"> \u003C\u002Fspan>\u003Cspan style=\"color:#ff7b72;font-weight:bold\">=\u003C\u002Fspan>\u003Cspan style=\"color:#6e7681\"> \u003C\u002Fspan>cfg.las.as_ref().unwrap().access_log.as_ref().unwrap();\u003Cspan style=\"color:#6e7681\">\n\u003C\u002Fspan>\u003C\u002Fspan>\u003C\u002Fspan>\u003Cspan style=\"display:flex;\">\u003Cspan>\u003Cspan style=\"color:#6e7681\">\u003C\u002Fspan>\u003Cspan style=\"color:#6e7681\">    \u003C\u002Fspan>\u003Cspan style=\"color:#ff7b72\">let\u003C\u002Fspan>\u003Cspan style=\"color:#6e7681\"> \u003C\u002Fspan>\u003Cspan style=\"color:#ff7b72\">mut\u003C\u002Fspan>\u003Cspan style=\"color:#6e7681\"> \u003C\u002Fspan>watcher\u003Cspan style=\"color:#6e7681\"> \u003C\u002Fspan>\u003Cspan style=\"color:#ff7b72;font-weight:bold\">=\u003C\u002Fspan>\u003Cspan style=\"color:#6e7681\"> \u003C\u002Fspan>LogWatcher::register(filename.to_string()).unwrap();\u003Cspan style=\"color:#6e7681\">\n\u003C\u002Fspan>\u003C\u002Fspan>\u003C\u002Fspan>\u003Cspan style=\"display:flex;\">\u003Cspan>\u003Cspan style=\"color:#6e7681\">\u003C\u002Fspan>\u003Cspan style=\"color:#6e7681\">    \u003C\u002Fspan>\u003Cspan style=\"color:#ff7b72\">let\u003C\u002Fspan>\u003Cspan style=\"color:#6e7681\"> \u003C\u002Fspan>\u003Cspan style=\"color:#ff7b72\">mut\u003C\u002Fspan>\u003Cspan style=\"color:#6e7681\"> \u003C\u002Fspan>poly: \u003Cspan style=\"color:#f0883e;font-weight:bold\">Poly\u003C\u002Fspan>\u003Cspan style=\"color:#6e7681\"> \u003C\u002Fspan>\u003Cspan style=\"color:#ff7b72;font-weight:bold\">=\u003C\u002Fspan>\u003Cspan style=\"color:#6e7681\"> \u003C\u002Fspan>Poly::new();\u003Cspan style=\"color:#6e7681\">\n\u003C\u002Fspan>\u003C\u002Fspan>\u003C\u002Fspan>\u003Cspan style=\"display:flex;\">\u003Cspan>\u003Cspan style=\"color:#6e7681\">\u003C\u002Fspan>\u003Cspan style=\"color:#6e7681\">\n\u003C\u002Fspan>\u003C\u002Fspan>\u003C\u002Fspan>\u003Cspan style=\"display:flex;\">\u003Cspan>\u003Cspan style=\"color:#6e7681\">\u003C\u002Fspan>\u003Cspan style=\"color:#6e7681\">    \u003C\u002Fspan>watcher.watch(\u003Cspan style=\"color:#ff7b72;font-weight:bold\">&\u003C\u002Fspan>\u003Cspan style=\"color:#ff7b72\">mut\u003C\u002Fspan>\u003Cspan style=\"color:#6e7681\"> \u003C\u002Fspan>\u003Cspan style=\"color:#ff7b72;font-weight:bold\">|\u003C\u002Fspan>line: String\u003Cspan style=\"color:#ff7b72;font-weight:bold\">|\u003C\u002Fspan>\u003Cspan style=\"color:#6e7681\"> \u003C\u002Fspan>{\u003Cspan style=\"color:#6e7681\">\n\u003C\u002Fspan>\u003C\u002Fspan>\u003C\u002Fspan>\u003Cspan style=\"display:flex;\">\u003Cspan>\u003Cspan style=\"color:#6e7681\">\u003C\u002Fspan>\u003Cspan style=\"color:#6e7681\">        \u003C\u002Fspan>poly.clone().push(line);\u003Cspan style=\"color:#6e7681\">\n\u003C\u002Fspan>\u003C\u002Fspan>\u003C\u002Fspan>\u003Cspan style=\"display:flex;\">\u003Cspan>\u003Cspan style=\"color:#6e7681\">\u003C\u002Fspan>\u003Cspan style=\"color:#6e7681\">        \u003C\u002Fspan>LogWatcherAction::None\u003Cspan style=\"color:#6e7681\">\n\u003C\u002Fspan>\u003C\u002Fspan>\u003C\u002Fspan>\u003Cspan style=\"display:flex;\">\u003Cspan>\u003Cspan style=\"color:#6e7681\">\u003C\u002Fspan>\u003Cspan style=\"color:#6e7681\">    \u003C\u002Fspan>})\u003Cspan style=\"color:#6e7681\">\n\u003C\u002Fspan>\u003C\u002Fspan>\u003C\u002Fspan>\u003Cspan style=\"display:flex;\">\u003Cspan>\u003Cspan style=\"color:#6e7681\">\u003C\u002Fspan>}\u003Cspan style=\"color:#6e7681\">\n\u003C\u002Fspan>\u003C\u002Fspan>\u003C\u002Fspan>\u003C\u002Fcode>\u003C\u002Fpre>\n\n\u003Cp>由此可见，闭包与函数还是有区别的。但是回调函数定义为Fn\u002FFnMut类型就可以同时接受闭包和函数类型的回调参数。举例如下\u003C\u002Fp>\n\n\u003Cpre style=\"color:#e6edf3;background-color:#0d1117;white-space:pre-wrap;word-break:break-word;\">\u003Ccode>\u003Cspan style=\"display:flex;\">\u003Cspan>\u003Cspan style=\"color:#ff7b72\">let\u003C\u002Fspan>\u003Cspan style=\"color:#6e7681\"> \u003C\u002Fspan>a\u003Cspan style=\"color:#6e7681\"> \u003C\u002Fspan>\u003Cspan style=\"color:#ff7b72;font-weight:bold\">=\u003C\u002Fspan>\u003Cspan style=\"color:#6e7681\"> \u003C\u002Fspan>String::from(\u003Cspan style=\"color:#a5d6ff\">"\u003C\u002Fspan>\u003Cspan style=\"color:#a5d6ff\">abc\u003C\u002Fspan>\u003Cspan style=\"color:#a5d6ff\">"\u003C\u002Fspan>);\u003Cspan style=\"color:#6e7681\">\n\u003C\u002Fspan>\u003C\u002Fspan>\u003C\u002Fspan>\u003Cspan style=\"display:flex;\">\u003Cspan>\u003Cspan style=\"color:#6e7681\">\u003C\u002Fspan>\u003Cspan style=\"color:#6e7681\">\n\u003C\u002Fspan>\u003C\u002Fspan>\u003C\u002Fspan>\u003Cspan style=\"display:flex;\">\u003Cspan>\u003Cspan style=\"color:#6e7681\">\u003C\u002Fspan>\u003Cspan style=\"color:#ff7b72\">let\u003C\u002Fspan>\u003Cspan style=\"color:#6e7681\"> \u003C\u002Fspan>\u003Cspan style=\"color:#ff7b72\">mut\u003C\u002Fspan>\u003Cspan style=\"color:#6e7681\"> \u003C\u002Fspan>x\u003Cspan style=\"color:#6e7681\"> \u003C\u002Fspan>\u003Cspan style=\"color:#ff7b72;font-weight:bold\">=\u003C\u002Fspan>\u003Cspan style=\"color:#6e7681\"> \u003C\u002Fspan>\u003Cspan style=\"color:#ff7b72;font-weight:bold\">|\u003C\u002Fspan>\u003Cspan style=\"color:#ff7b72;font-weight:bold\">|\u003C\u002Fspan>\u003Cspan style=\"color:#6e7681\"> \u003C\u002Fspan>println!\u003Cspan style=\"color:#6e7681\">\u003C\u002Fspan>(\u003Cspan style=\"color:#6e7681\">\u003C\u002Fspan>\u003Cspan style=\"color:#a5d6ff\">"\u003C\u002Fspan>\u003Cspan style=\"color:#a5d6ff\">x \u003C\u002Fspan>\u003Cspan style=\"color:#a5d6ff\">{}\u003C\u002Fspan>\u003Cspan style=\"color:#a5d6ff\">"\u003C\u002Fspan>,\u003Cspan style=\"color:#6e7681\"> \u003C\u002Fspan>a);\u003Cspan style=\"color:#6e7681\">\n\u003C\u002Fspan>\u003C\u002Fspan>\u003C\u002Fspan>\u003Cspan style=\"display:flex;\">\u003Cspan>\u003Cspan style=\"color:#6e7681\">\u003C\u002Fspan>\u003Cspan style=\"color:#6e7681\">\n\u003C\u002Fspan>\u003C\u002Fspan>\u003C\u002Fspan>\u003Cspan style=\"display:flex;\">\u003Cspan>\u003Cspan style=\"color:#6e7681\">\u003C\u002Fspan>\u003Cspan style=\"color:#ff7b72\">fn\u003C\u002Fspan> \u003Cspan style=\"color:#d2a8ff;font-weight:bold\">y\u003C\u002Fspan>()\u003Cspan style=\"color:#6e7681\"> \u003C\u002Fspan>{\u003Cspan style=\"color:#6e7681\">\n\u003C\u002Fspan>\u003C\u002Fspan>\u003C\u002Fspan>\u003Cspan style=\"display:flex;\">\u003Cspan>\u003Cspan style=\"color:#6e7681\">\u003C\u002Fspan>\u003Cspan style=\"color:#6e7681\">    \u003C\u002Fspan>println!\u003Cspan style=\"color:#6e7681\">\u003C\u002Fspan>(\u003Cspan style=\"color:#6e7681\">\u003C\u002Fspan>\u003Cspan style=\"color:#a5d6ff\">"\u003C\u002Fspan>\u003Cspan style=\"color:#a5d6ff\">y\u003C\u002Fspan>\u003Cspan style=\"color:#a5d6ff\">"\u003C\u002Fspan>)\u003Cspan style=\"color:#6e7681\">\n\u003C\u002Fspan>\u003C\u002Fspan>\u003C\u002Fspan>\u003Cspan style=\"display:flex;\">\u003Cspan>\u003Cspan style=\"color:#6e7681\">\u003C\u002Fspan>}\u003Cspan style=\"color:#6e7681\">\n\u003C\u002Fspan>\u003C\u002Fspan>\u003C\u002Fspan>\u003Cspan style=\"display:flex;\">\u003Cspan>\u003Cspan style=\"color:#6e7681\">\u003C\u002Fspan>\u003Cspan style=\"color:#6e7681\">\n\u003C\u002Fspan>\u003C\u002Fspan>\u003C\u002Fspan>\u003Cspan style=\"display:flex;\">\u003Cspan>\u003Cspan style=\"color:#6e7681\">\u003C\u002Fspan>\u003Cspan style=\"color:#ff7b72\">fn\u003C\u002Fspan> \u003Cspan style=\"color:#d2a8ff;font-weight:bold\">wrap\u003C\u002Fspan>(c: \u003Cspan style=\"color:#79c0ff\">&\u003C\u002Fspan>\u003Cspan style=\"color:#f0883e;font-weight:bold\">mut\u003C\u002Fspan>\u003Cspan style=\"color:#6e7681\"> \u003C\u002Fspan>Fn())\u003Cspan style=\"color:#6e7681\"> \u003C\u002Fspan>{\u003Cspan style=\"color:#6e7681\">\n\u003C\u002Fspan>\u003C\u002Fspan>\u003C\u002Fspan>\u003Cspan style=\"display:flex;\">\u003Cspan>\u003Cspan style=\"color:#6e7681\">\u003C\u002Fspan>\u003Cspan style=\"color:#6e7681\">    \u003C\u002Fspan>c()\u003Cspan style=\"color:#6e7681\">\n\u003C\u002Fspan>\u003C\u002Fspan>\u003C\u002Fspan>\u003Cspan style=\"display:flex;\">\u003Cspan>\u003Cspan style=\"color:#6e7681\">\u003C\u002Fspan>}\u003Cspan style=\"color:#6e7681\">\n\u003C\u002Fspan>\u003C\u002Fspan>\u003C\u002Fspan>\u003Cspan style=\"display:flex;\">\u003Cspan>\u003Cspan style=\"color:#6e7681\">\u003C\u002Fspan>\u003Cspan style=\"color:#6e7681\">\n\u003C\u002Fspan>\u003C\u002Fspan>\u003C\u002Fspan>\u003Cspan style=\"display:flex;\">\u003Cspan>\u003Cspan style=\"color:#6e7681\">\u003C\u002Fspan>wrap(\u003Cspan style=\"color:#ff7b72;font-weight:bold\">&\u003C\u002Fspan>\u003Cspan style=\"color:#ff7b72\">mut\u003C\u002Fspan>\u003Cspan style=\"color:#6e7681\"> \u003C\u002Fspan>x);\u003Cspan style=\"color:#6e7681\"> \u003C\u002Fspan>\u003Cspan style=\"color:#8b949e;font-style:italic\">\u002F\u002F pass a closure\n\u003C\u002Fspan>\u003C\u002Fspan>\u003C\u002Fspan>\u003Cspan style=\"display:flex;\">\u003Cspan>\u003Cspan style=\"color:#8b949e;font-style:italic\">\u003C\u002Fspan>wrap(\u003Cspan style=\"color:#ff7b72;font-weight:bold\">&\u003C\u002Fspan>\u003Cspan style=\"color:#ff7b72\">mut\u003C\u002Fspan>\u003Cspan style=\"color:#6e7681\"> \u003C\u002Fspan>y);\u003Cspan style=\"color:#6e7681\"> \u003C\u002Fspan>\u003Cspan style=\"color:#8b949e;font-style:italic\">\u002F\u002F pass a function\n\u003C\u002Fspan>\u003C\u002Fspan>\u003C\u002Fspan>\u003C\u002Fcode>\u003C\u002Fpre>\n\n\u003Cp>同样可以参考 \u003Cstrong>stackoverflow\u003C\u002Fstrong> 的这个\u003Ca href=\"https:\u002F\u002Fstackoverflow.com\u002Fquestions\u002F52696907\u002Fwhy-does-passing-a-closure-to-function-which-accepts-a-function-pointer-not-work\">提问\u003C\u002Fa>。\u003C\u002Fp>\n",{"title":18,"list":19},"最热文章",[20,26,32,38,44,50,56,62,68,74],{"id":21,"title":22,"uri":23,"author":10,"created_at":24,"view_count":25},28,"docker容器目录与主机目录同步","\u002Farticle\u002Fdocker容器目录与主机目录同步","2014-12-31 12:34:08",15570,{"id":27,"title":28,"uri":29,"author":10,"created_at":30,"view_count":31},21,"beego中使用fis","\u002Farticle\u002Fbeego中使用fis","2014-12-03 10:47:56",9250,{"id":33,"title":34,"uri":35,"author":10,"created_at":36,"view_count":37},20,"用github登录，oauth开发","\u002Farticle\u002F用github登录，oauth开发","2014-11-23 13:33:37",9113,{"id":39,"title":40,"uri":41,"author":10,"created_at":42,"view_count":43},18,"windows服务注册工具nssm","\u002Farticle\u002Fwindows服务注册工具nssm","2014-10-31 21:34:39",9047,{"id":45,"title":46,"uri":47,"author":10,"created_at":48,"view_count":49},49,"用latex排版中文书籍","\u002Farticle\u002F用latex排版中文书籍","2016-10-31 11:12:02",8634,{"id":51,"title":52,"uri":53,"author":10,"created_at":54,"view_count":55},19,"texlive中文书签乱码","\u002Farticle\u002Ftexlive中文书签乱码","2014-11-15 02:54:01",8461,{"id":57,"title":58,"uri":59,"author":10,"created_at":60,"view_count":61},6,"Windows上的软件包管理器chocolatey","\u002Farticle\u002FWindows上的软件包管理器chocolatey","2014-08-10 15:55:22",8009,{"id":63,"title":64,"uri":65,"author":10,"created_at":66,"view_count":67},3,"利用开源和免费资源搭建CI环境","\u002Farticle\u002F利用开源和免费资源搭建CI环境","2014-07-04 16:54:58",7732,{"id":69,"title":70,"uri":71,"author":10,"created_at":72,"view_count":73},16,"php-fpm网站目录权限配置","\u002Farticle\u002Fphp-fpm网站目录权限配置","2014-10-18 01:36:10",7274,{"id":75,"title":76,"uri":77,"author":10,"created_at":78,"view_count":79},27,"sublime text 2插件开发，外部修改文件无法重新加载","\u002Farticle\u002Fsublime text 2插件开发，外部修改文件无法重新加载","2014-12-26 20:24:13",7054,{"title":81,"list":82},"按月归档",[83,87,90,93,96,99,102,106,110,113,116,119,123,126,129,133,136,139,142,146,149,152,155,158,161,164,167,170,173,176,179,182,185,188,191,194,197,200,203,206,210,213,216,219,222,225],{"title":84,"uri":85,"view_count":86},"2026年7月","\u002Farchive\u002F2026\u002F7\u002F1","[1]",{"title":88,"uri":89,"view_count":86},"2026年1月","\u002Farchive\u002F2026\u002F1\u002F1",{"title":91,"uri":92,"view_count":86},"2025年4月","\u002Farchive\u002F2025\u002F4\u002F1",{"title":94,"uri":95,"view_count":86},"2024年6月","\u002Farchive\u002F2024\u002F6\u002F1",{"title":97,"uri":98,"view_count":86},"2024年5月","\u002Farchive\u002F2024\u002F5\u002F1",{"title":100,"uri":101,"view_count":86},"2024年4月","\u002Farchive\u002F2024\u002F4\u002F1",{"title":103,"uri":104,"view_count":105},"2023年12月","\u002Farchive\u002F2023\u002F12\u002F1","[6]",{"title":107,"uri":108,"view_count":109},"2023年11月","\u002Farchive\u002F2023\u002F11\u002F1","[2]",{"title":111,"uri":112,"view_count":86},"2023年10月","\u002Farchive\u002F2023\u002F10\u002F1",{"title":114,"uri":115,"view_count":86},"2023年7月","\u002Farchive\u002F2023\u002F7\u002F1",{"title":117,"uri":118,"view_count":109},"2023年6月","\u002Farchive\u002F2023\u002F6\u002F1",{"title":120,"uri":121,"view_count":122},"2023年5月","\u002Farchive\u002F2023\u002F5\u002F1","[3]",{"title":124,"uri":125,"view_count":109},"2023年4月","\u002Farchive\u002F2023\u002F4\u002F1",{"title":127,"uri":128,"view_count":109},"2023年3月","\u002Farchive\u002F2023\u002F3\u002F1",{"title":130,"uri":131,"view_count":132},"2023年2月","\u002Farchive\u002F2023\u002F2\u002F1","[5]",{"title":134,"uri":135,"view_count":86},"2023年1月","\u002Farchive\u002F2023\u002F1\u002F1",{"title":137,"uri":138,"view_count":109},"2022年12月","\u002Farchive\u002F2022\u002F12\u002F1",{"title":140,"uri":141,"view_count":132},"2022年11月","\u002Farchive\u002F2022\u002F11\u002F1",{"title":143,"uri":144,"view_count":145},"2022年10月","\u002Farchive\u002F2022\u002F10\u002F1","[4]",{"title":147,"uri":148,"view_count":105},"2022年9月","\u002Farchive\u002F2022\u002F9\u002F1",{"title":150,"uri":151,"view_count":132},"2022年8月","\u002Farchive\u002F2022\u002F8\u002F1",{"title":153,"uri":154,"view_count":86},"2019年7月","\u002Farchive\u002F2019\u002F7\u002F1",{"title":156,"uri":157,"view_count":86},"2019年2月","\u002Farchive\u002F2019\u002F2\u002F1",{"title":159,"uri":160,"view_count":86},"2018年9月","\u002Farchive\u002F2018\u002F9\u002F1",{"title":162,"uri":163,"view_count":86},"2018年8月","\u002Farchive\u002F2018\u002F8\u002F1",{"title":165,"uri":166,"view_count":86},"2017年11月","\u002Farchive\u002F2017\u002F11\u002F1",{"title":168,"uri":169,"view_count":86},"2017年8月","\u002Farchive\u002F2017\u002F8\u002F1",{"title":171,"uri":172,"view_count":86},"2017年5月","\u002Farchive\u002F2017\u002F5\u002F1",{"title":174,"uri":175,"view_count":86},"2017年4月","\u002Farchive\u002F2017\u002F4\u002F1",{"title":177,"uri":178,"view_count":86},"2016年11月","\u002Farchive\u002F2016\u002F11\u002F1",{"title":180,"uri":181,"view_count":86},"2016年10月","\u002Farchive\u002F2016\u002F10\u002F1",{"title":183,"uri":184,"view_count":109},"2016年9月","\u002Farchive\u002F2016\u002F9\u002F1",{"title":186,"uri":187,"view_count":86},"2016年8月","\u002Farchive\u002F2016\u002F8\u002F1",{"title":189,"uri":190,"view_count":109},"2016年7月","\u002Farchive\u002F2016\u002F7\u002F1",{"title":192,"uri":193,"view_count":132},"2016年6月","\u002Farchive\u002F2016\u002F6\u002F1",{"title":195,"uri":196,"view_count":86},"2015年12月","\u002Farchive\u002F2015\u002F12\u002F1",{"title":198,"uri":199,"view_count":86},"2015年10月","\u002Farchive\u002F2015\u002F10\u002F1",{"title":201,"uri":202,"view_count":109},"2015年2月","\u002Farchive\u002F2015\u002F2\u002F1",{"title":204,"uri":205,"view_count":86},"2015年1月","\u002Farchive\u002F2015\u002F1\u002F1",{"title":207,"uri":208,"view_count":209},"2014年12月","\u002Farchive\u002F2014\u002F12\u002F1","[8]",{"title":211,"uri":212,"view_count":109},"2014年11月","\u002Farchive\u002F2014\u002F11\u002F1",{"title":214,"uri":215,"view_count":132},"2014年10月","\u002Farchive\u002F2014\u002F10\u002F1",{"title":217,"uri":218,"view_count":122},"2014年9月","\u002Farchive\u002F2014\u002F9\u002F1",{"title":220,"uri":221,"view_count":122},"2014年8月","\u002Farchive\u002F2014\u002F8\u002F1",{"title":223,"uri":224,"view_count":122},"2014年7月","\u002Farchive\u002F2014\u002F7\u002F1",{"title":226,"uri":227,"view_count":109},"2013年9月","\u002Farchive\u002F2013\u002F9\u002F1",1,{"url":230,"title":231},"https:\u002F\u002Fimage.duguying.net\u002F2022\u002F09\u002Fij6x8o4s.webp","老家 摄于2020年秋",1790062272557]