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POUnable to call a function stored as string from inside a class
 

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    <p><strong>EDIT: Sorry guys, it was a typo =(</strong></p> <p>I feel embarrassed for wasting your time on this. I'm leaving this thread open in hopes that someone might find the discussed information useful.</p> <p><em>To clarify further, the code below will work as expected, I mistyped 'classHandler' in my code, and that's the reason PHP couldn't find it.</em></p> <p><em>Also, the syntax errors noted by some commenters have been corrected</em></p> <p>I feel obligated to summarize the discussion on this thread:</p> <hr> <p>@wimvds suggests using inheritance and that my implementation is not a good practice.</p> <p>@Victor Nicollet disagrees saying extending the behavior of an existing instance is 1. impossible and 2. bad design</p> <p>@ircmaxell adds: Remember, you should always favor composition over inheritance. And this isn't spaghetti code, it's a pretty standard method of implementing a stripped down notification system (You could build a full blown observer or mediator pattern, but for really simple tasks, this may be a whole lot better since it's easier to maintain).</p> <p>@Victor asks for a minimal one file example returning this error. This is what helped me solve the issue. When I tried the sample file, it work perfectly leading me to believe that something else indeed was wrong.</p> <p>@Shakti Singh suggests trying <code>call_user_func( array( $this, $this-&gt;handler ), $var);</code></p> <p>@Victor Nicollet responds saying This would attempt to call a member function $this->classHandler (which probably doesn't exist) instead of the global classHandler</p> <p>@abesto gives it a shot, ends up with a very similar implementation as my own, which works without my typo.</p> <p>@Victor Nicollet answers by claiming that the classHandler needs to be defined prior to the call.</p> <p>@Blizz responds by saying that PHP parses classes and functions first and then the regular code.</p> <hr> <p><strong>MyClass.php</strong> ( singleton )</p> <pre><code>public $handler; public function myMethod() { $var = "test"; call_user_func( $this-&gt;handler, $var ); // PHP Warning: First argument is expected to be a valid callback } </code></pre> <p><strong>Script.php</strong></p> <pre><code>$myClass = new MyClass; $myClass-&gt;handler = "classHandler"; $myClass-&gt;myMethod(); function classHandler( $var ) { echo $var; } </code></pre> <p>If this is incorrect, what is the commonly practiced means of invoking handlers / event handlers in php?</p> <p><em>Note that this is a simplified version of the actual script</em></p>
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    1. COthere are a lot of syntax errors in the script. A new class instance is made by `$myClass = new MyClass` for example
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    2. COThis should work just fine as long as `classHandler` is a regular function and not a class method. Syntax issues aside, what are your exact errors/who isn't it working?
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    3. COOk, but the question you should ask yourself first is : why are you not overriding your myMethod function - or use a relevant pattern on your OO code? Because now you're creating spaghetti code that will take ages to understand/debug for someone who didn't write it...
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