Access a variable nested in a function inside a class in php

class mainClass {
    public $username;
    function  __construct($username){
        $this->username = $username;
    }

    function myForm() {
        echo '<input type="text" value="'.$this->userName.'" />';
    }

 }

 function mainFunction () {
    $myArray = array (
        'child_of' => $this->username;
    );
 }

can value of 'userName' be available out side 'mainClass' so that I can use it anywhere?

Yes.

First, you need to define a class property like this

class MainClass
{

    private $_userName;

    public function myForm()
    {
        echo '<input type="text" value="'.$this->_userName.'" />';
    }
}

Look at how you access this property inside the myForm() method.

Then you need to define getter method for this property (or you can make the property public) like this:

class MainClass
{

    private $_userName;

    public function getUserName()
    {
        return $this->_userName;
    }

    public function myForm()
    {
        echo '<input type="text" value="'.$this->_userName.'" />';
    }
}

You can access user name property like this

$main = new MainClass();
$userName = $main->getUserName();

Note that you need an instance of the MainClass class.

I suggest you to start with simple concept and make sure you understand this 100%. Also I would suggest avoid using global variables and more complicated logic with static methods. Try to make it as simple as possible.

Warm regards, Victor

The below code is a very minimized version of the Codeigniter get_instance method. So in your case you can have somewhere at the beginning this code:

/** Basic Classes to load the logic and do the magic */

class mainInstance {

    private static $instance;

    public function __construct()
    {
        self::$instance =& $this;
    }

    public static function &get_instance()
    {
        return self::$instance;
    }
}

function &get_instance()
{
    return mainInstance::get_instance();
}

new mainInstance();
/** ----------------------------------------------- */

and then you can create your global Classes like this:

class customClass1 {

    public $userName = '';

      function myForm() {
          return '<input type="text" value="'.$this->userName.'" />';
       }

}

/** This is now loading globally */
$test = &get_instance();
//If you choose to actually create an object at this instance, you can call it globally later
$test->my_test = new customClass1(); 
$test->my_test->userName = "johnny";

/** The below code can be wherever in your project now (it is globally) */
$test2 = &get_instance();
echo $test2->my_test->myForm()."<br/>"; //This will print: <input type="text" value="johnny" />
echo $test2->my_test->userName; //This will printing: johnny

As this is now globally you can even create your own function like this:

function mainFunction () {
    $tmp = &get_instance();
    return $tmp->my_test->userName;
}

echo mainFunction();