范围与括号在C + + [英] Scope with Brackets in C++

问题描述

有任何情况下，放置代码在括号内减少其范围是我可能想做的，或者是这些情况下，你们会告诉我，如果你需要在你的代码，那么你的代码写得很糟。

例如：

  // *** CODE **** 
 {
 int foo = stuff; 
 //使用foo，然后我永远使用它
} 
 // ****更多的代码**** 
  
 
 
解决方案
是的，因为这样做的优点是，该块中的任何局部变量都将在块。如果你想要尽快发布一些范围保护，例如
  {
 std :: lock_guard< std :: mutex> lock（the_mutex）; 
 //使用受保护对象
} //释放the_mutex 
  
 ，使用像这样的范围块表示您的代码需要重构：块的内容通常可以拆分为一个单独的函数，可以命名和重用。
 
Is there any case in which putting code within brackets to reduce its scope is something that I might want to do, or is this one of those cases in which you guys will tell me, "If you need to do that in your code, then your code is badly written."

For example:
//***CODE****
{
  int foo=stuff;
  //use foo, and then I'm done using it forever
}
//****MORE CODE****

解决方案
Yes, because this has the advantage that any local variables in that block will be destroyed at the end of the block.  This is especially useful if you have some kind of scope guard that you want to release as soon as possible, e.g.,
{
    std::lock_guard<std::mutex> lock(the_mutex);
    // use protected objects
}   // release the_mutex
Note, however, that the use of a scope block like this is indicative of your code needing to be refactored:  the contents of the block can usually be split out into a separate function, which can be named and reused.

                        
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