Question

Quick OO question

Asked by: Fatlog

hi,  quick OO question for ya!

i have a few objects which extend each other. I create an instance of one object(A) and then within that object i create an instance of another object(B). I then want to be able to access the the values within A's variables from B...

class A
{
 protected var1;
 protected childObject;
 function __construct()
 {
  $this->var1 = "Hello";
  $this->childObject = new B();
 }
}

class B extends A
{
 function __construct()
 {
  // i want to access the value in A->var1 here. i.e...
  echo $this->var1;
 }
}

i realise its only the class members/methods that are inherited by the child class but i want to access the values within the variables also. currently i pass a reference of the object to the child after i create it...

$this->childObject->B =& $this;

or something similar. but this seems messy to me. is there any way to just have the variable values accessible by the newly instantiated class??

thanks

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Asked On
2008-04-04 at 05:20:11ID23295736
Tags

PHP

Topic

PHP Scripting Language

Participating Experts
1
Points
50
Comments
6

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Answers

 

by: RQuadlingPosted on 2008-04-04 at 05:27:07ID: 21280878

PHP4 or PHP5? Important differences between the two and I don't want to get you confused (I'll get confused as well!)

 

by: RQuadlingPosted on 2008-04-04 at 05:32:08ID: 21280930

Ah.

Having REALLY read your code!

<?php
class aParent
	{
	protected
		$o_Child,
		$s_Name;
	function __construct()
		{
		$this->s_Name = 'Parental';
		$this->o_Child = new aChild($this);
		}
	
	}
 
class aChild extends aParent
	{
	protected
		$o_Parent;
	function __construct(aParent $o_Parent)
		{
		$this->o_Parent = $o_Parent;
		echo $this->o_Parent->s_Name;
		}
	}
 
$o_Parent = new aParent();
?>

                                              
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by: FatlogPosted on 2008-04-04 at 06:25:50ID: 21281380

nice and simple!

tho should the child class really inherit from the parent class in this basic example?
it can access the parent classes methods and variables using $this->s_Name but now also has $this->o_Parent->s_Name to access the values.

 

by: RQuadlingPosted on 2008-04-04 at 06:29:13ID: 21281413

No.
Different instance!

The first instance is just a parent.

This creates a child and tells it that who its parent is.

The newly created child can also be a parent (child extends parent).

So, the name of the parent is a different property to the child's name.

 

by: RQuadlingPosted on 2008-04-04 at 06:37:53ID: 21281486

Without running it, what do you think the output will be?

<?php
class aParent
        {
        public
                $o_Child,
                $s_Name;
 
        function __construct()
                {
                $this->s_Name = 'Parent';
                }
        
        }
 
class aChild extends aParent
        {
        public
                $o_Parent;
 
        function __construct(aParent $o_Parent)
                {
                $this->o_Parent = $o_Parent;
		$this->s_Name = 'Child';
                }
        }
 
$o_Parent = new aParent();
$o_Child = new aChild($o_Parent);
echo 'Parental name      : ', $o_Parent->s_Name, PHP_EOL;
echo 'Child name         : ', $o_Child->s_Name, PHP_EOL;
echo 'Child->Parent name : ', $o_Child->o_Parent->s_Name, PHP_EOL;
?>

                                              
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by: FatlogPosted on 2008-04-04 at 07:36:15ID: 21282174

ah yeah...
hadn't occurred to me when i was writing the above. child member is overloading parent member.

20120131-EE-VQP-002

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