检查变量的值时，反向条目（null === $ value）的含义是什么？ [英] What's the meaning of the reverse entry (null === $value) when checking the value of the variable?

问题描述

可能重复：

PHP - 在if语句中颠倒顺序

检查空 - 什么订单？

检查Zend Framework发现他们以相反的方式执行所有变量检查：

Examining Zend Framework found that they do all the variable checkings reverse way:

public function setBootstrap($path, $class = null) {

   if (null === $class) {    // instead of if($class === null)
      $class = 'Bootstrap';
   }

这样做的原因是什么？

这是否也适合Java和C ++编程？

Is this also suitable for Java and C++ programming?

推荐答案

有些人认为它有助于他们避免写一个 = （一个赋值而不是相等的比较）

some people believe it helps them in avoiding to write a single = (an assignment instead of a comparison for equality)

我相信这样做的好处远远低于可读性的损失（因此可维护性！）

I believe that the advantage of doing so is much less than the loss of readability (and therefore maintainability!)

不测试代码的人可能会依赖这种技巧。并且回答你的问题，是的，它适用于从C语言派生语法的大多数语言 - 我的意思是合适的，不推荐。

People who don't test their code may rely on this sort of trick. And to answer your question, yes, it is suitable for most languages who derive their syntax from C - I mean suitable, not recommended.

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