question about OOP

[AL-Kateb]

Hi everybody, sorry i don't know how to title this topic, and that's why i was not able to search for an answer on google or here in the forums so i thought i should go ahead and post this question.

i have class A and class B, class B will be initiated from within class A and it will be assigned to a property of class A so calling any method in class be will be like this:

$A->B->method();

but while I'm inside class B i might want to access a property from class A! using this will refer to class B itself! what can i do about that? of course using "parent" has nothing to do with this cos B does not inherit class A it was just initiated inside it.

here is an example code:

class classOne{
    var $classTwo;
	function __construct(){
	  $this->classTwo = new classTwo;
	}
	function testOne(){
		return "HiOne";
	}
}

class classTwo{
	function testTwo(){
		return ????->testOne;
	}
}
$class_one = new classOne;
echo $class_one->classTwo->testTwo();

how can i access testOne from within testTwo? or this is not possible?

well so far all i can do is doing like this
echo $class_one->classTwo->testTwo($class_one);

so if i pass the class object by reference and use it there it would be possible but that's not what i am looking for.

so if there is anyway to achieve this, please let me know.

Thanks

[sneakyimp]

When one class creates an instance of the other, it should assign itself as a property of the newly created class.

class classOne{
    var $classTwo;
    function __construct(){
      $this->classTwo = new classTwo;
      $this->classTwo->creator = $this; // this class assigns itself as creator
    }
    function testOne(){
        return "HiOne";
    }
}

class classTwo{
    private $creator; // we have a var to hold a reference to the creator

function testTwo(){
    return $this->creator->testOne;
}
}
$class_one = new classOne;
echo $class_one->classTwo->testTwo(); 

[AL-Kateb]

Hey sneakyimp, thanks for your reply.

i did not think of it this way : )

though we won't be able to make it work while the creator property is private as the first class will have to assign a value to that, it has to be public.

plus i think it would be better if we pass the creator by reference instead of having another instance of the same object.

Thanks again.

class classOne{
    var $classTwo;
    function __construct(){
      $this->classTwo = new classTwo;
      $this->classTwo->creator =& $this; // this class assigns itself as creator
    }
    function testOne(){
        return "HiOne";
    }
}

class classTwo{
    var $creator; // we have a var to hold a reference to the creator

function testTwo(){
    return $this->creator->testOne();
}
}
$class_one = new classOne;
echo $class_one->classTwo->testTwo();

[johanafm]

You could also have the classTwo take classOne as a constructor argument

class ClassTwo
{
	public function __construct(ClassOne &$c)
	{
		$this->creator = $c;
	}
}

class ClassOne
{
	# works in constructor as well
	public function someFunc()
	{
		$this->contained = new ClassTwo($this);
	}
}

Or, you could pass the container objects reference to any call to the contained class' methods

class ClassTwo
{
	public function __construct() {	}

# foo() needs creator access
public function foo(ClassOne &$c)
{
	# ...
}
# bar needs creator access
public function bar(ClassOne &$c)
{
	# ...
}
# baz() doesn't
public function baz()
{
	# ...
}
}

Or, you could even NOT pass the creator instance to the contained instance, but rather pass along those things for which access is needed.

class ClassOne
{
	$propOne;
	$propTwo;
	$classTwo;
	public function foo()
	{
		$this->classTwo->twoFoo($this->propOne);
	}
	public function bar()
	{
		$this->classTwo->twoBar($this->propTwo);
	}
}

Also, if classTwo needs so much classOne access, perhaps you're not using the proper deisgn, and classTwo should rather extend classOne.