Re: PEAR_Autoloader

<LingWitt@insightbb.com> wrote : > I've been using PEAR_Autoloader to create what is known in ObjC as > delegation (Its not actually a language feature though). The idea is > that an object (or multiple objects) can be made the delegate of > another object. When this relationship is established, the delegate > gets a reference to the "owning" object so that it can perform certain > tasks on the object (if required). Thus, with the __call method, it is > like adding already implemented interfaces to an object. This feature > is pretty rudimentary, but powerful, and it seems like it would be an > interesting addition to the PEAR package. The setup could be as follows: > > interface PEAR_DelegateInterface > { > public function setOwner($owner); > public function getOwner(); > } > > class PEAR_DelegateOwner extends PEAR_Autoloader > { > public function addDelegate($classname) > { > $this->addAggregateObject($classname); > } > > public function addAggregateObject($classname) > { > $classname = strtolower($classname); > if (!class_exists($classname)) { > $include_file = preg_replace('/[^a-z0-9]/i', '_', > $classname); > include_once $include_file; > } > $obj = new $classname; > if ($obj instanceof PEAR_DelegateInterface) > { > $obj->setOwner($this); > } > else > { > return; > } > $methods = get_class_methods($classname); > foreach ($methods as $method) { > // don't import priviate methods and constructors > if ($method{0} != '_' && $method != $classname) { > $this->_method_map[$method] = $obj; > } > } > } > } > > As an example: > > class Delegate implements PEAR_DelegateInterface > { > var $_owner; > > public function setOwner($owner) > { > $this->_owner = $owner; > } > > public function getOwner() > { > return $this->_owner; > } > > public function hello() > { > $this->_owner->_message = "Hello!"; > } > } > > class Foo extends PEAR_DelegateOwner > { > var $_message = "hi"; > } > > $foo = new FOO(); > $foo->addDelegate("Delegate"); > $foo->hello(); > > $foo->_message now says hello. An object can only have one delegate, so your method should be setDelegate(), not addDelegate(). Also, I am not sure it's a good idea to set a owner in the delegate, after all, the delegate shouldn't care who's its owner. Then hello() could be hello($owner), but I think that having the delegate modify its owner is probably not a good thing, just a feeling I have. I see a delegate as a slave. The slave can't change the master. I am also not sure an owner needs to know about all the methods in its delegate, I think it should just test if a method_exists() in the delegate before calling that method. An owner could probably have a special instance var with the delegate methods it is likely to call. Delegates would be a really cool addition to PHP. Bertrand Mansion Mamasam