[RESOLVED] Accessing properties - objects within objects

thunderace

This is my first post here so hi all.

Environment PHP5

I am having difficulties working out the best way to access properties when my objects are within objects. I'll try to explain clearly.

Class A - has a property $this->value = "Hello World";

Class B is instantiated in Class A

Class C is instantiated in Class B

B and C do not and cannot extend A

In class C I wish to access $value from Class A.

The only way I can seem to do this atm is by passing the whole of class A as an object into Class C which ofc seems stupid, and I don't want to use global.

I'm sure I'm missing something obvious so any and all help appreciated.

laserlight

The only way I can seem to do this atm is by passing the whole of class A as an object into Class C which ofc seems stupid.

That is the correct thing to do, except that C will not have ownership for the A object, so it only holds a reference (or a pointer) to A.

thunderace

Interesting .. thanks for the reply laserlight.

As it is only a reference then I suppose there is little overhead too, just seems wrong
as Class C is effectively running within A anyway.

laserlight

As it is only a reference then I suppose there is little overhead too, just seems wrong
as Class C is effectively running within A anyway.

The C object only knows about itself and its members. It does not know that it belongs to a B object that belongs to an A object... and indeed it may not be the case since you could use it in another context.

If PHP allowed nested classes, then perhaps you could nest B in A and C in B, in which case C really would know that it belongs to a B that belongs to an A, but PHP does not have that language feature.

thunderace

Thanks laserlight,

It was becoming obvious to me that the properties of A were out of scope but I needed clarification that I wasn't missing something obvious and you have answered my question superbly.

Thanks for your time.

laserlight

No problem 🙂
Remember to mark this thread as resolved using the thread tools.

NogDog

If C is only interested in one particular value that happens to be in A, and if C is to be more generally usable and not strictly dependent upon an A object, perhaps you could just pass the one particular value it needs to it? You could even pass it by reference so that modifications to it in object A will be reflected when C uses it:

<?php

class A
{
   private $var = '';
   private $b;
   public function __construct()
   {
      $this->b = new B($this->var);
   }
   public function hello()
   {
      $this->var = 'World';
      $this->b->hello();
   }
}

class B
{
   private $var;
   private $c;
   public function __construct(&$var)
   {
      $this->var =& $var;
      $this->c = new C($this->var);
   }
   public function hello()
   {
      $this->c->hello();
   }
}

class C
{
   private $var;
   public function __construct(&$var)
   {
      $this->var =& $var;
   }
   public function hello()
   {
      echo "Hello, " . $this->var . "!";
   }
}

$test = new A();
$test->hello(); // outputs "Hello, World!"

?>

thunderace

Glad I found this forum it seems to be exactly what I needed to feed my overtaxed PHP brain.

What I eventually ended up doing was to create static methods/properties in A.

What I was looking to achieve was to have A as the encompassing class for the whole script and within A there is e.g. a method reusableFunctions ..

  public static function reusableFunctions() {

self::$func = new ReusableFunctions;
self::$xhtml = new XhtmlOutput;

  }

By creating static methods and properties I am able to reuse these reusable functions throughout the script .. like ..

FWRK::$func->isDigit($thisnumber);

I really appreciated the help I was given in this thread and post what I eventually did in case others may be considering similar (or ofc to be ripped to threads if you all think this a bad idea 🙂 )