Emulate public/private properties with __get() and __set()? - php

Question

I was writing a class that uses __get() and __set() to store and retrieve array elements in a master array. I had a check to make some elements ungettable, basically to re-create private properties.
I noticed that it seemed that __get intercepts all calls to class properties. This sucks for me, because I wanted to have a variable private to the outside world ( unavailable via get ), but I was trying to access it by directly referencing the master array from within the class. Of course, the master array is not in the whitelist of gettable properties :(
Is there a way I can emulate public and private properties in a php class that uses __get() and __set()?
Example:
<?
abstract class abstraction {
private $arrSettables;
private $arrGettables;
private $arrPropertyValues;
private $arrProperties;
private $blnExists = FALSE;
public function __construct( $arrPropertyValues, $arrSettables, $arrGettables ) {
$this->arrProperties = array_keys($arrPropertyValues);
$this->arrPropertyValues = $arrPropertyValues;
$this->arrSettables = $arrSettables;
$this->arrGettables = $arrGettables;
}
public function __get( $var ) {
echo "__get()ing:\n";
if ( ! in_array($var, $this->arrGettables) ) {
throw new Exception("$var is not accessible.");
}
return $this->arrPropertyValues[$var];
}
public function __set( $val, $var ) {
echo "__set()ing:\n";
if ( ! in_array($this->arrSettables, $var) ) {
throw new Exception("$var is not settable.");
}
return $this->arrPropertyValues[$var];
}
} // end class declaration
class concrete extends abstraction {
public function __construct( $arrPropertyValues, $arrSettables, $arrGettables ) {
parent::__construct( $arrPropertyValues, $arrSettables, $arrGettables );
}
public function runTest() {
echo "Accessing array directly:\n";
$this->arrPropertyValues['color'] = "red";
echo "Color is {$this->arrPropertyValues['color']}.\n";
echo "Referencing property:\n";
echo "Color is {$this->color}.\n";
$this->color = "blue";
echo "Color is {$this->color}.\n";
$rand = "a" . mt_rand(0,10000000);
$this->$rand = "Here is a random value";
echo "'$rand' is {$this->$rand}.\n";
}
}
try {
$objBlock = & new concrete( array("color"=>"green"), array("color"), array("color") );
$objBlock->runTest();
} catch ( exception $e ) {
echo "Caught Exeption $e./n/n";
}
// no terminating delimiter
$ php test.php
Accessing array directly:
__get()ing:
Caught Exeption exception 'Exception' with message 'arrPropertyValues is not accessible.' in /var/www/test.php:23
Stack trace:
#0 /var/www/test.php(50): abstraction->__get('arrPropertyValu...')
#1 /var/www//test.php(68): concrete->runTest()
#2 {main}.

Answer 1

Is there a way I can emulate public and private properties in a php class that uses __get() and __set()?
Not directly (if you discount debug_backtrace).
But you can have a private method getPriv that does all the work your current __get does. Then __get would only wrap this private method and check accessibility.
function __get($name) {
if (in_array($name, $this->privateProperties))
throw new Exception("The property ". __CLASS__ . "::$name is private.");
return $this->getPriv($name);
}
Inside your class, you would call getPriv, thus bypassing __get.

Answer 2

Make abstraction::$arrPropertyValues protected or do what Artefacto wrote (if you need additional checks), except that abstraction::getPriv() should be protected.

Answer 3

Rather than manually enlisting private/protected properties, you could use PHPs cumbersome reflection methods:
function __get($name) {
$reflect = new ReflectionObject($this);
$publics = $reflect->getProperties(ReflectionProperty::IS_PUBLIC);
if (in_array($name, $publics)) {
return $this->{$name};
}
}