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    <p>The kind of chaining you are referring to there involves returning not <code>$this</code>, but a new object representing the data found. The trick is to make that object usable <em>as though</em> it were an array or scalar, using <a href="http://php.net/manual/en/language.oop5.magic.php" rel="nofollow">"magic methods"</a> and <a href="http://uk1.php.net/manual/en/reserved.interfaces.php" rel="nofollow">pre-defined interfaces</a>.</p> <p><a href="http://php.net/manual/en/book.simplexml.php" rel="nofollow">The SimpleXML extension</a> makes extensive use of this concept so that every object can simultaneously be used in multiple ways:</p> <ul> <li><code>__toString()</code>, so that casting to a string, or using in an unambiguous string context like <code>echo</code> gives you the text content of an XML node</li> <li><a href="http://uk1.php.net/manual/en/class.arrayaccess.php" rel="nofollow">ArrayAccess</a> so that you can use <code>$a['href']</code> to access attributes, and <code>$li[42]</code> to access one of multiple matching nodes</li> <li><a href="http://uk1.php.net/manual/en/class.iterator.php" rel="nofollow">Iterator</a> so that you can <code>foreach</code> over multiple matches</li> <li><code>__get()</code> and <code>__set()</code> to search for and over-write child elements by tag name</li> </ul> <p>(Actually, SimpleXML is a binary extension, so cheats a bit, but most of its functionality could theoretically be implemented in plain PHP using the above.)</p> <p>So for instance this statement:</p> <pre><code>echo $simplexml_element-&gt;foo[42]-&gt;bar['baz']; </code></pre> <p>appears to contain arrays, hashes, and strings, but is actually a whole chain of object calls, something like this:</p> <pre><code>echo $simplexml_element-&gt;__get('foo')-&gt;offsetGet(42)-&gt;__get('bar')-&gt;offsetGet('baz')-&gt;__toString(); </code></pre>
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    1. POHow does a fluid interface return both $this and a value?
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    1. COAhhh now that explains what I'm seeing. I guess a lot more studying is in order to fully understand what's going on. You wouldn't perhaps have any pointers or good reading on the subject to get me on my way would you?
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    2. COHm, not sure. I'm a bit of a "learn by example" type myself, so tend to nose into other people's code and experiment rather than wading through tutorials and the like...
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