#variable variables

This bit of code sent me on a quest to understand variable variables and how they can seem confusing when used with the $this object.

<?php class SomeClass {       private $email;       private $password;       public function __set($name, $value)       {             $this->$name = $value;        } } Everything I thought about Class Methods told me that this should be $this->name = $value.  This however will not work. The problem as i understand it is that $this->name suggests that name is a property of the object $this.  The only properties of $this are $email and $password and should therefore be accessed by $this->email or $this->password. The magic method __set() is called automatically when an object is created with parameters that are inaccessible (or don't exist).  In the code above, when we are coding the magic method __set(), we don't know whether we are acting on $email, $password or some other non-existent property. So how do we solve this.  Well one very neat way is to use the dynamic properties of variable variables.  Basically, as it is with $value where we want this to act as a kind of  place holder and directly place the value of $value into the function, we also want to place the value of $name directly into the function.  Therefore we make use of the variable variables concept and use $this->$name = $value instead of $this->name = $value.

Resources::

For a general explanation of variable variables:

http://uk1.php.net/manual/en/language.variables.variable.php

For a tutorial on magic methods that uses $this->$name: