Polymorphism problems

daarius

Java code:

public class Parent {
   // implementation

   public integer create(int val) {
      // implementation
   }
}


public class Child extends Parent {
   // implementation

   public integer create(int val) {
      super.create(val);
      // my further implementation
   }
}

myObj = new Child();
myObj.create(val);

now i did this in php:

class Parent {
   // implementation

   function create($val) {
      // implementation
   }
}


class Child extends Parent {
   // implementation

   function create($val) {
      $this->create($val);
      // my further implementation
   }
}

$myObj = new Child();
$myObj->create(val);

above, actually crashes the PHP (atleast on webserver). no respond page is displayed.

Any other workarounds using this methodology? anyone came across something like this? i know there are solutions, e.g. in child class have function myCreate() and then call $this->create(); within myCreate()...

but that would be something extra to remember for the users, and also could be misleading i.e. the different name.

is there any other way of calling Super method in PHP? i think this is solved in Zend2 with parent-> and self-> etc... or not?

regards,
Daarius...

jeremuck

I don't think so.

PHP's class functionality isn't the best.
I wouldn't consider it a true OOP language because it violates some of the most fundamental tenants.
(What information hiding?)

PHP doesn't keep a tight reign on variable typing, so I think what you want to do is impossible.
I suppose you could edit the source of PHP to add this functionality, and thousands of people would be grateful...

You will have to re-implement the whole thing

in the child's function copy and paste the source from the parent's function and then add additional implementation.

EDIT: I forgot, you can use Java classes in PHP.
$object = new java("myparentclass");

jeremuck

I'm sorry I was completely wrong.

http://www.php.net/manual/en/keyword.parent.php


class Parent {
                                 // implementation

                             function create($val) {
                                // implementation
                             }
                          }


                          class Child extends Parent {
                             // implementation

                             function create($val) {
                                parent::create($val);
                                // my further implementation
                             }
                          }

                          $myObj = new Child();
                          $myObj->create(val);

ednark

agreed that php::oop is sucky....

i have found myself faking mulitple-inheritance by doing this:

class A
{
 var $parent_b;
 var $parent_c;
 function A()
 {
   $this->parent_b = new B();
   $this->parent_c = new C();
 }
}

though this does not give you the real goody of inheritnace, transparency...
Iif you are reading the changelgos on 4.3 you will notice they have fixed afew things about how objects work.. and have added try-catch functionality... yay!!!!

... search ...

hmmm... i can't for the life of me find the docs on the whats new in the php 4.3.0pre releases.... but i swear to you ive read them...

mabye someone else would be generous enough to post where they may be found

daarius

yes, that is true. i was aware of parent::create() example. but this is not exactly what i am trying to achieve. Its a simple "class-method" call, i.e. static call to create().

what we need is something like parent->create(); so that create() can access the class attributes, the "instantiated ones".

do you know what i mean?

daarius

ok, sorry. Please mind my ignorance!

Although the syntax does look like static "class-method" call, but it does actually work. parent::create(); does have access to initialised attributes of the class.

why? because the whole thing is instantiated anyway!!

regards,
Daarius...