Why is the usage of $this in PHP necessary when referencing methods or variables in the same class?

Question

I was explaining to a Java developer why his method call wasn\'t working. He just needed to add $this->method_name();

He then asked me, \"Why do

Answer 1

That's just how scope works in PHP. $obj->f() refers to $foo in the function scope. If you want to get the class property $obj->foo within f(), it's $this->foo.

global $foo;
$foo = 99;

class myclass
{
    public $foo;

    function f()
    {
        $this->foo = 12;
        $foo = 7;

        // $this->foo != $foo != $GLOBALS['foo']
    }
}