C++ 实现Golang里的defer

不多说了，直接贴代码。就一个hpp文件。

 1 #include <functional>
 2
 3 #define CONCAT_(a, b) a##b
 4 #define CONCAT(a, b) CONCAT_(a,b)
 5 /*
 6 eg. defer(代码);  注意后面 一定要加上 ;
 7 */
 8
 9 #define defer(code) DeferOp CONCAT(_defer_, __LINE__) = [&](){code}
10
11 class DeferOp
12 {
13 public:
14     DeferOp(std::function<void()>&& fn)
15         : m_fun(std::move(fn))
16     {}
17     ~DeferOp()
18     {
19         if (nullptr != m_fun)
20         {
21             m_fun();
22         }
23     }
24
25 #if _MSC_VER >= 1700    //VS2012
26     DeferOp(DeferOp &&other) = delete;
27     DeferOp(const DeferOp&) = delete;
28     void operator=(const DeferOp &) = delete;
29 #else
30     DeferOp(DeferOp &&other);
31     DeferOp(const DeferOp&);
32     void operator=(const DeferOp &);
33 #endif
34 protected:
35     std::function<void()> m_fun;
36 };

使用方法：

1 {
2   defer
3     (
4       //代码
5     );
6 }    

再加个 vs 代码片段

 1 <?xml version="1.0" encoding="utf-8"?>
 2 <CodeSnippets xmlns="http://schemas.microsoft.com/VisualStudio/2005/CodeSnippet">
 3     <CodeSnippet Format="1.0.0">
 4         <Header>
 5             <Title>defer</Title>
 6             <Shortcut>defer</Shortcut>
 7             <Description>延迟的代码片段</Description>
 8             <Author>bin432</Author>
 9             <SnippetTypes>
10                 <SnippetType>Expansion</SnippetType>
11                 <SnippetType>SurroundsWith</SnippetType>
12             </SnippetTypes>
13         </Header>
14         <Snippet>
15             <Declarations>
16                 <Literal>
17
18                 </Literal>
19             </Declarations>
20             <Code Language="cpp"><![CDATA[defer
21     (
22             $selected$ $end$
23     );]]>
24             </Code>
25         </Snippet>
26     </CodeSnippet>
27 </CodeSnippets>

保存为defer.snippet文件，放到C:\Program Files (x86)\Microsoft Visual Studio\2017\Community\Common7\IDE\VC\Snippets\2052\Visual C++目录。

这个目录可以在vs的 工具-代码片段管理器 就可以找到。

完毕！！！