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！！！