more info.. http://evergreenphp.blogspot.com
Many developers writing object-oriented applications create one PHP source file per-class definition.
One of the biggest annoyances is having to write a long list of needed includes at the beginning of each
script (one for each class).
In PHP 5, this is no longer necessary. You may define an __autoload function which is automatically
called in case you are trying to use a class/interface which hasn't been defined yet. By calling this
function the scripting engine is given a last chance to load the class before PHP fails with an error.
Note: Exceptions thrown in __autoload function cannot be caught in the catch block and
results in a fatal error.
Note: Autoloading is not available if using PHP in CLI interactive mode.
Note: If the class name is used e.g. in call_user_func() then it can contain some dangerous
characters such as../. It is recommended to not use the user-input in such functions or at
least verify the input in__autoload().
}$obj= new MyClass1();
$obj2 = new MyClass2();