Does PHP copy object data structures when I pass objects to functions or methods?
<p>I know there's the option to pass a value by reference, simply by writing something like </p>

<pre><code>function foo(&amp;$bar) {...}
</code></pre>

<p>But from Objective-C I'm used to believe that objects are <em>always</em> passed by reference (since the variables referencing them are just pointers whose values are just a memory address). Only sctructures and primitives would have to explicitely be passed by reference.</p>

<p>How's that going on in PHP? Must I be sure to put that address operator &amp; into every parameter to enhance performance when passing objects?</p>
