Quick OOP Question

[bigft]

Hey I've got a quick question regarding a OOP problem.

 

The thing is, is that I have a main file (A), and it has two variables (B, and C) that both hold separate classes, class B is the mysql functions and class C is the error functions. What I need to know is how to access the error function in class C from class B.

 

For example, (i know this is retarded), but in my mysql class, for the error display I have:

 

mysql_query(......) or parent::C->SetError('omgawd....');

 

And I know this doesn't work, but it may set an example on what I'm looking for.

 

Any help would be appreciated.

 

edit ...(Crap sorry, didn't realize there was an OOP forum before posting)

[corbin]

Well, to access a class, you have to have a reference to it...  So, how would you go about doing that?

 

-You could pass it as an argument to the second class.

class class1 {
     public function Func() {
          echo 'Hi';
     }
}

$c1 = new Class1;

class class2 {
     private $class1;
     public function __construct($class1) {
          $this->class1 = $class1;
     }
     public function DoSomethingWithC1() {
         $this->class1->Func();
      }
}

$c2 = new Class2($c1);
$c2->DoSomethingWithC1();

 

Or, you could always globalize it.  (I would avoid this way.)

class class1 {
     public function Func() {
          echo 'Hi';
     }
}

$c1 = new Class1;

class class2 {
     public function DoSomethingWithC1() {
          global $c1;
          $c1->Func();         
      }
}

$c2 = new Class2($c1);
$c2->DoSomethingWithC1();

 

 

Or, you could have a singleton, allowing you to get the reference from anywhere without passing or globalizing...

(This is an extremely simple example.)

 

function GetInst() {
     static $inst = null;
     if($inst == null) {
          $inst = new Class1;
     }
     return $isnt;
}
//Please note that this always returns the exact same class.


//then, throughout the script, you can just do...
GetInst()->Func();

 

Anyway, hopefully one of those will work for you, and someone else can probably expand on my answer, since I don't know much about OOP.

[keeB]

I can't think of a reason why you would want to keep an objects state in another class.

 

Can you please elaborate on what you are trying to accomplish?

[bigft]

I don't think I explained it to well, here's an example of what I'm trying to do:

 

<?php
class class1{
var $c2;
var $c3;
etc...
.
.
}

class class2{

function error($msg){
	return $msg;
	etc....
}

}

class class3{
function query($sql){
	return mysql_query($sql) or error('can\'t run query...');
}
}

$c1 = new class1;
$c1->c2 = class2;
$c1->c3 = class3;
?>

 

What I'm trying to do is use the error function from class2, in class3.

 

Also, I realized that I never extended the classes so I can't use the parent scope (well I think i can't anyways).

[DarkWater]

Make them static methods or instantiate new objects for use inside of the class.  IE:

class Settings {
  protected $db;
  protected $user;

  __construct(DB $db, User $user) {
   $this->db = $db;
   $this->user = $user;
  }

  public function ChangeAvatar {
     //do some stuff with $this->db and $this->user
  }
}

 

Then, assuming you have a DB and User class, you could do:

$db = new DB;

$user = new User("DarkWater");

$settings = new Settings($db, $user);

 

[keeB]

I think using Error as a case is not a good idea to begin with, because you really should be using Exceptions.

 

Corbin provided you with 2 good examples on how to achieve what you would like.