[{"data":1,"prerenderedAt":230},["ShallowReactive",2],{"article-closure-can-not-use-var-outsite-the-closure-function":3},{"title":4,"article":5,"hot_article":16,"month_arch":79,"cover":227},"初学rust，闭包引用外部变量 - 独孤影的博客",{"id":6,"title":7,"uri":8,"author":9,"tags":10,"created_at":13,"view_count":14,"content":15},74,"初学rust，闭包引用外部变量","closure-can-not-use-var-outsite-the-closure-function","duguying",[11,12],"rust","闭包","2022-09-27 22:44:09",408,"\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":17,"list":18},"最热文章",[19,25,31,37,43,49,55,61,67,73],{"id":20,"title":21,"uri":22,"author":9,"created_at":23,"view_count":24},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",15573,{"id":26,"title":27,"uri":28,"author":9,"created_at":29,"view_count":30},21,"beego中使用fis","\u002Farticle\u002Fbeego中使用fis","2014-12-03 10:47:56",9253,{"id":32,"title":33,"uri":34,"author":9,"created_at":35,"view_count":36},20,"用github登录，oauth开发","\u002Farticle\u002F用github登录，oauth开发","2014-11-23 13:33:37",9115,{"id":38,"title":39,"uri":40,"author":9,"created_at":41,"view_count":42},18,"windows服务注册工具nssm","\u002Farticle\u002Fwindows服务注册工具nssm","2014-10-31 21:34:39",9054,{"id":44,"title":45,"uri":46,"author":9,"created_at":47,"view_count":48},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",8645,{"id":50,"title":51,"uri":52,"author":9,"created_at":53,"view_count":54},19,"texlive中文书签乱码","\u002Farticle\u002Ftexlive中文书签乱码","2014-11-15 02:54:01",8466,{"id":56,"title":57,"uri":58,"author":9,"created_at":59,"view_count":60},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",8012,{"id":62,"title":63,"uri":64,"author":9,"created_at":65,"view_count":66},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",7740,{"id":68,"title":69,"uri":70,"author":9,"created_at":71,"view_count":72},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",7276,{"id":74,"title":75,"uri":76,"author":9,"created_at":77,"view_count":78},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",7055,{"title":80,"list":81},"按月归档",[82,86,89,92,95,98,101,105,109,112,115,118,122,125,128,132,135,138,141,145,148,151,154,157,160,163,166,169,172,175,178,181,184,187,190,193,196,199,202,205,209,212,215,218,221,224],{"title":83,"uri":84,"view_count":85},"2026年7月","\u002Farchive\u002F2026\u002F7\u002F1","[1]",{"title":87,"uri":88,"view_count":85},"2026年1月","\u002Farchive\u002F2026\u002F1\u002F1",{"title":90,"uri":91,"view_count":85},"2025年4月","\u002Farchive\u002F2025\u002F4\u002F1",{"title":93,"uri":94,"view_count":85},"2024年6月","\u002Farchive\u002F2024\u002F6\u002F1",{"title":96,"uri":97,"view_count":85},"2024年5月","\u002Farchive\u002F2024\u002F5\u002F1",{"title":99,"uri":100,"view_count":85},"2024年4月","\u002Farchive\u002F2024\u002F4\u002F1",{"title":102,"uri":103,"view_count":104},"2023年12月","\u002Farchive\u002F2023\u002F12\u002F1","[6]",{"title":106,"uri":107,"view_count":108},"2023年11月","\u002Farchive\u002F2023\u002F11\u002F1","[2]",{"title":110,"uri":111,"view_count":85},"2023年10月","\u002Farchive\u002F2023\u002F10\u002F1",{"title":113,"uri":114,"view_count":85},"2023年7月","\u002Farchive\u002F2023\u002F7\u002F1",{"title":116,"uri":117,"view_count":108},"2023年6月","\u002Farchive\u002F2023\u002F6\u002F1",{"title":119,"uri":120,"view_count":121},"2023年5月","\u002Farchive\u002F2023\u002F5\u002F1","[3]",{"title":123,"uri":124,"view_count":108},"2023年4月","\u002Farchive\u002F2023\u002F4\u002F1",{"title":126,"uri":127,"view_count":108},"2023年3月","\u002Farchive\u002F2023\u002F3\u002F1",{"title":129,"uri":130,"view_count":131},"2023年2月","\u002Farchive\u002F2023\u002F2\u002F1","[5]",{"title":133,"uri":134,"view_count":85},"2023年1月","\u002Farchive\u002F2023\u002F1\u002F1",{"title":136,"uri":137,"view_count":108},"2022年12月","\u002Farchive\u002F2022\u002F12\u002F1",{"title":139,"uri":140,"view_count":131},"2022年11月","\u002Farchive\u002F2022\u002F11\u002F1",{"title":142,"uri":143,"view_count":144},"2022年10月","\u002Farchive\u002F2022\u002F10\u002F1","[4]",{"title":146,"uri":147,"view_count":104},"2022年9月","\u002Farchive\u002F2022\u002F9\u002F1",{"title":149,"uri":150,"view_count":131},"2022年8月","\u002Farchive\u002F2022\u002F8\u002F1",{"title":152,"uri":153,"view_count":85},"2019年7月","\u002Farchive\u002F2019\u002F7\u002F1",{"title":155,"uri":156,"view_count":85},"2019年2月","\u002Farchive\u002F2019\u002F2\u002F1",{"title":158,"uri":159,"view_count":85},"2018年9月","\u002Farchive\u002F2018\u002F9\u002F1",{"title":161,"uri":162,"view_count":85},"2018年8月","\u002Farchive\u002F2018\u002F8\u002F1",{"title":164,"uri":165,"view_count":85},"2017年11月","\u002Farchive\u002F2017\u002F11\u002F1",{"title":167,"uri":168,"view_count":85},"2017年8月","\u002Farchive\u002F2017\u002F8\u002F1",{"title":170,"uri":171,"view_count":85},"2017年5月","\u002Farchive\u002F2017\u002F5\u002F1",{"title":173,"uri":174,"view_count":85},"2017年4月","\u002Farchive\u002F2017\u002F4\u002F1",{"title":176,"uri":177,"view_count":85},"2016年11月","\u002Farchive\u002F2016\u002F11\u002F1",{"title":179,"uri":180,"view_count":85},"2016年10月","\u002Farchive\u002F2016\u002F10\u002F1",{"title":182,"uri":183,"view_count":108},"2016年9月","\u002Farchive\u002F2016\u002F9\u002F1",{"title":185,"uri":186,"view_count":85},"2016年8月","\u002Farchive\u002F2016\u002F8\u002F1",{"title":188,"uri":189,"view_count":108},"2016年7月","\u002Farchive\u002F2016\u002F7\u002F1",{"title":191,"uri":192,"view_count":131},"2016年6月","\u002Farchive\u002F2016\u002F6\u002F1",{"title":194,"uri":195,"view_count":85},"2015年12月","\u002Farchive\u002F2015\u002F12\u002F1",{"title":197,"uri":198,"view_count":85},"2015年10月","\u002Farchive\u002F2015\u002F10\u002F1",{"title":200,"uri":201,"view_count":108},"2015年2月","\u002Farchive\u002F2015\u002F2\u002F1",{"title":203,"uri":204,"view_count":85},"2015年1月","\u002Farchive\u002F2015\u002F1\u002F1",{"title":206,"uri":207,"view_count":208},"2014年12月","\u002Farchive\u002F2014\u002F12\u002F1","[8]",{"title":210,"uri":211,"view_count":108},"2014年11月","\u002Farchive\u002F2014\u002F11\u002F1",{"title":213,"uri":214,"view_count":131},"2014年10月","\u002Farchive\u002F2014\u002F10\u002F1",{"title":216,"uri":217,"view_count":121},"2014年9月","\u002Farchive\u002F2014\u002F9\u002F1",{"title":219,"uri":220,"view_count":121},"2014年8月","\u002Farchive\u002F2014\u002F8\u002F1",{"title":222,"uri":223,"view_count":121},"2014年7月","\u002Farchive\u002F2014\u002F7\u002F1",{"title":225,"uri":226,"view_count":108},"2013年9月","\u002Farchive\u002F2013\u002F9\u002F1",{"url":228,"title":229},"https:\u002F\u002Fimage.duguying.net\u002F2022\u002F09\u002Fij6x8o4s.webp","老家 摄于2020年秋",1790781593854]