title: Is there any benefit of using null first in PHP?
body: <blockquote>
    <p><strong>Possible Duplicate:</strong><br>
    <a href="https://stackoverflow.com/questions/3309089/why-do-some-experienced-programmers-write-expressions-this-way">Why do some experienced programmers write comparisons with the value before the variable?</a>  </p>
  </blockquote>
  
  
  
  <p>I am just curious about this: in most frameworks/opensource projects I have studied, I often seen code like this...</p>
  
  <pre><code>&lt;?php
  
  if (null === self::$_instance) {
      self::$_instance = new self();
  }
  </code></pre>
  
  <p>In particular this line...</p>
  
  <pre><code>if (null === self::$_instance) {
  </code></pre>
  
  <p>Why use <code>null</code> in the first argument of the <code>if</code> statement instead of the other way around?...</p>
  
  <pre><code>if (self::$_instance === null) {
  </code></pre>
  
  <p>I realize there is probably no performance increase or anything like that. Is this just a preference or is it some kind of coding standard I have overlooked?</p>