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[2010-10-22 13:00 UTC] tom at r dot je
Description:
------------
as it stands, it's possible to create a wrapper e.g.
<?php
class A {
}
class AWrapper {
protected $a;
public function __construct(A $a) {
$this->a = $a;
}
public function __set($name, $value) {
$this->a->$name = $value;
}
public function __get($name) {
return $this->a->$name;
}
public function __call($func, $args) {
return call_user_func_array(array($this->a, $func), $args);
}
}
?>
AWrapper, now mimics the interface of A. It will work as a substitute for A, anywhere A is required.
The problem is, type checking. Anywhere class "A" is used, it may be type hinted or checked using instanceof
e.g.
function setA(A $a) {
}
or $foo isntanceof 'A';
If an __instanceof magic method existed, it would be possible to get around this and have true wrapper classes.
For example:
public function __instanceof() {
return 'A';
}
Or perhaps it should return an array to allow it to wrap multiple classes.
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Last updated: Sun May 19 02:01:35 2024 UTC |
Why is that? While that solution works, it's clunky. For example for debugging/logging I may want to do something prior to each method call: class Wrapper { protected $object; private function log($details) { } public function __construct($object) { $this->object = $object; } public function __set($name, $value) { $this->object->$name = $value; } public function __get($name) { return $this->object->$name; } public function __call($func, $args) { $this->log('Called ' . $func); return call_user_func_array(array($this->object, $func), $args); } } ?> Essentially the adapter pattern for any object. This works until you pass it around. Extending the A wont work because: __call will never get called because the methods exist Also, this wrapper class could wrap *any* class in the system. Extending every class isn't viable.