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POPHP: Cannot redeclare class error after return
 

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  1. POPHP: Cannot redeclare class error after return
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    <p>I'm trying to protect classes being redeclared by returning based on if class_exists. This is common when creating plugins in Wordpress as there may be multiple plugins using the same classes. Using the following trivial example:</p> <p>You can view this on Youtube at <a href="http://www.youtube.com/watch?v=llVTvh6ffmw" rel="nofollow">http://www.youtube.com/watch?v=llVTvh6ffmw</a></p> <p>The following link demonstrates the problem and the root cause <a href="http://www.youtube.com/watch?v=VcNLoDvRLDc" rel="nofollow">http://www.youtube.com/watch?v=VcNLoDvRLDc</a></p> <p><strong>index.php</strong></p> <pre><code>&lt;?php include_once('debug1.php'); include_once('debug2.php'); $test = new SomeClass(); echo $test-&gt;someVar; </code></pre> <p><strong>debug1.php</strong> &amp; <strong>debug2.php</strong> are duplicate files...</p> <pre><code>&lt;?php if(class_exists('SomeClass')) return; class SomeClass { var $someVar = "test"; } </code></pre> <p>Despite having a return statement we still get a fatal error "cannot redeclare class".</p> <p>On a side note: Oddly 80% of the time this code has worked by simply adding/removing whitespace in debug2 - by work I mean it runs once then it breaks.</p> <p>I am running PHP version 5.4.4.</p> <p>So my question is. Is this expected behaviour? If yes, what am I missing. If no, is worrying as I've seen this in a few Wordpress plugins.</p> <p>Please note: I can get it to work every time with else wrapping, but this is more code...:</p> <pre><code>&lt;?php if(class_exists('SomeClass')) return; else { class SomeClass { var $someVar = "test"; } } </code></pre>
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    1. COThis problem is best solved with autoloading, so it doesn't make any sense to suggest alternative approaches unless you give specific constraints up front (and explain why they cannot be lifted).
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      1. USJon
    2. COThanks Jon - your right autoloading would bypass this problem but am more interested in whether this is expected behaviour especially as other well known plugins use it e.g. [Wordpres Github Plugin Updater](https://github.com/jkudish/WordPress-GitHub-Plugin-Updater/blob/master/updater.php)
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    3. COIt is expected behavior, yes. And again, it doesn't make sense to do things like that unless you are operating under particular constraints.
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