Question

I have been told that a class cannot be defined within a class in PHP. However, in my own example this seems to work which has me confused:

class_test.php:

require('class_1.php');
new class_1
//Need $missing_variable here.

class_1.php

class class_1{
    public function function_1(){
        function callback_function(){
            echo "A Callback";
            $missing_variable = "Where Did I Go?";
        }
        require('class_2.php');
        new class_2('callback_function');
    }
    public function __construct(){
        $this->function_1();
    }
}

class_2.php

class class_2{
    public function __construct($callback){
        echo "Hello World - ";
        call_user_func($callback);
    }
}

Loading class_test.php prints out

Hello World - A Callback

Question: How do I define $missing_variable such that I can get it where I need it?

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In case anyone in the future has a similar problem, however unlikely that may be, I want to link to the codepad from below that shows the $missing_variable echo’d from outside the classes:

http://codepad.org/tRk0XWG7

Thanks again everyone.

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^{Note: This is a follow up.}

Answer 1

You would return $missing_variable in a few places. See below. (This isn’t the only way to do it, mind you)

http://codepad.org/tf08Vgdx

<?
class class_2{
    public function __construct($callback){
        echo "Hello World - ";
        $missing = $callback();
        $this->missing = $missing;
    }
}
class class_1{
    public function function_1(){
        function callback_function(){
            echo "A Callback. ";
            $missing_variable = "Where Did I Go?";
            return $missing_variable;
        }
        $class2 = new class_2('callback_function');
        return $class2->missing;
    }
    public function __construct(){
        $this->missing = $this->function_1();
    }
}

$class = new class_1();

echo $class->missing;