Where are PHP model classes defined for use?
<p>I was wondering where functions and classes are defined for php...</p>

<p>I remember looking at WordPress source, and they were calling functions without including files, so I'm curious where this stuff is defined. </p>

<p>What I'm looking at doing putting some connection code, like mysql or like for twilio below</p>

<pre><code>  require "sms/Twilio.php";
  $AccountSid = "AAAAAAAAAAAAAAAAAAAAAAAAAAAAA";
  $AuthToken = "BBBBBBBBBBBBBBBBBBBBBBBBBBBBB";
  $client = new Services_Twilio($AccountSid, $AuthToken);
</code></pre>

<p>I'm then thinking of putting just this in a file and including it in many places, but I'm curious if it can get easier than including a file. </p>
