PHP classes

[theS70RM]

Hi,

If I have a class that defines another class, how do i access the sub one from the main code.

So I have something like:
<?

class A{
   function A($foo){
       $this->p = new B($foo);  
 
   }
 
}
 
class B{
    function Z($myvar){
      $this->ID= $myvar;
 
   }
 
}
 
?>

But how would the main code go to access the ID property of B when an A has been defined... i.e. not like this:

$newvar = new A(666);
echo "B=".$newvar->p->ID;

how should it look?

thanks

Andy

[pbmods]

Heya, Andy.

The code you provided should work, since undeclared class members are assumed to be public in PHP.

A slightly more sane-looking approach might look something like this:

class A
{
  public $child;
 
  public function __construct( $subVal )
  {
    $this->child = new B($subVal);
  }
}
 
class B
{
  public $id;
 
  public function __construct( $id )
  {
    $this->id = $id;
  }
}
 
$newVar = new A(666);
echo "B = {$newVar->child->id}";
 

Alternatively, you might want A to be a wrapper for B. In this case, you might consider using magic methods to make the child class accessible:

class A
{
  protected $child;
 
  public function __construct( $subVal )
  {
    $this->child = new B($subVal);
  }
 
  public function __get( $var )
  {
    if( isset($this->child->$var) )
    {
      return $this->child->$var;
    }
    else
    {
      return null;
    }
  }
}
 
class B
{
  public $id;
 
  public function __construct( $id )
  {
    $this->id = $id;
  }
}
 
$newVar = new A(666);
echo "B = {$newVar->id}";
 

In the second example, PHP will look for A::$id, which doesn't exist, so it will instead call A::__get('id'), which will check to see if B::$id has been set.

[theS70RM]

Thanks, that helps alot. I'll have a look at applying this to my code.

[theS70RM]

a couple of questions..

class A
{
  public $id;
 
  public function __construct( $id )
  {
    $this->id = $id;
  }
}

how come function __construct(){} doesnt work for me,

how come I cant declare public functions or variables?

Cheers

[pbmods]

You are probably running PHP 4, which does not support these features.

Check out this document to see what features are available.

[theS70RM]

oh ok,

Yea i am using php4 and cant upgrade at the mo.

cheers

Andy