94 The Registry Pattern

The real magic in this alternative is the line $this->_store =& $GLOBALS[REGISTRY_GLOBAL_STORE;], where the reference operator binds the global array to the instance variable $_store. This is the key to MonoState implementations: each time $this->_store is used in the object, the actual effect is mirrored to the global variable.

But it hardly makes sense to recommend a solution based on global variables. A static class vari-able would be a better solution, if only PHP4 provided such a feature. Yet, is there a way to use refer-ences to implement a static class variable in your own code?

The tests can be similar to the RegistryGlobal tests:

class RegistryMonoStatePHP4TestCase extends UnitTestCase { function testRegistryMonoState() { $this->assertCopy(

$reg =& new RegistryMonoState ,$reg2 =& new RegistryMonoState); $this->assertFalse($reg->isValid(‘key’)); $this->assertNull($reg->get(‘key’)); $test_value = ‘something’; $reg->set(‘key’, $test_value);

$this->assertReference($reg->get(‘key’), $reg2->get(‘key’)); } }

To make your own class static variable, bind a reference to a function static variable to a class instance variable.

class RegistryMonoState { var $_store;

function &_initRegistry() {

static $store = array();

return $store; }

function RegistryMonoState() {

$this->_store =& $this->_initRegistry(); }

function isValid($key) {

return array_key_exists($key, $this->_store); }

function &get($key) {

if (array_key_exists($key, $this->_store)) return $this->_store[$key]; }