Yes you can do that but it's a pain to set them global too.
Do you know how to add properties to a class?
very simply you can do this:
Class MyTest
{
var $name;
function MyTest( $name)
{
$this->name = $name;
}
function alterName()
{
$this->name = strrev($this->name);
}//alterName
function showName()
{
echo $this->name;
}
}// end of class
$test = new MyTest();
$test->alterName();
$test->showName();