In a loop, a guard can have two special conditions tested against in addition to the standard Boolean test.
在一个循环中，除了标准的布尔测试外，一个约束能测试二个特定的条件式。
2
The standard way to handle this problem is to check first to see if logging is enabled before constructing expensive logging messages. In other words, use a guard clause like Listing 1.
解决这个问题的标准方式是在构造昂贵的日志消息之前，首先检查是否启用了日志。
3
Being the guard, academic editorial department should be on the duty to maintain academic standard.