title: How to deal with unwanted widget build?
body: <p>For various reasons, sometimes the <code>build</code> method of my widgets is called again.</p>
  <p>I know that it happens because a parent updated. But this causes undesired effects.
  A typical situation where it causes problems is when using <code>FutureBuilder</code> this way:</p>
  <pre><code>@override
  Widget build(BuildContext context) {
    return FutureBuilder(
      future: httpCall(),
      builder: (context, snapshot) {
        // create some layout here
      },
    );
  }
  </code></pre>
  <p>In this example, if the <em>build</em> method were to be called again, it would trigger another HTTP request. Which is undesired.</p>
  <p>Considering this, how to deal with the unwanted build? Is there any way to prevent a build call?</p>