[RESOLVED] accessing separate object inside a class

[lazzerous]

Ok - I'm having a brain fart.

Within one script, I have created an object from one class ($this->main).

I am calling another class ($this->newProjectForm) and I want to be able to access all of the contents and functionality of $this->main within the object $this->newProjectForm)

example code:

<?php
include once "class.main.php";
include_once "class.newProjectForm.php";

$this->main = new main();
$newProjectForm = new newProjectForm();
?>

I tried passing $this->main to newProjectForm as follows:

$newProjectForm = new newProjectForm($this->main);

And within the newProjectForm class, doing the following

class newProjectForm {
  var $main;
  function __construct($main_passed)
  {
    $this->main = $main_passed;
  }
}

But had no luck.

Where am I going wrong here?

Thanks in advance,
-=Lazz=-

[NogDog]

You were pretty close, but had an extraneous "$this->".

<?php
include once "class.main.php";
include_once "class.newProjectForm.php";

$main = new main();
$newProjectForm = new newProjectForm($main);
?> 

Or, if that's the only place you're going to use $main, you could even do:

$newProjectForm = new newProjectForm(new main());

[bretticus]

I assume you mean something like this...

<?php

class main {
	function __construct()
	{
		// empty for now
	}
	function some_main_method()
	{
		echo "hello world";
	}
}

class newProjectForm {
	var $main;
	function __construct()
	{
		$this->main = new main();
	}
	function some_project_function()
	{
		$this->main->some_main_method();
	}
}

$project = new newProjectForm();

?>

?

You can call main from newProjectForm. However, the proper way to do this is to extend main.

<?php
class main {
	function __construct()
	{
		// empty for now
	}
	function some_main_method()
	{
		echo "hello world";
	}
}

class newProjectForm extends main {
	function some_project_function()
	{
		$this->some_main_method();
	}
}

$project = new newProjectForm();
?>

[bretticus]

Keep in mind, in the following code, if you end up merely passing a newly instantiated main to your newProjectForm, you will simply be cloning the main.

<?php
class newProjectForm {
  var $main;
  function __construct($main_passed)
  {
    $this->main = $main_passed;
  }
} 

include_once "class.main.php";
include_once "class.newProjectForm.php";

$main = new main();
$newProjectForm = new newProjectForm($main);
/*
if I set properties for main in newProjectForm just now, I can't access them from the object instance of $main.
$main->some_prop may be different than $newProjectForm->main->some_prop
*/

However, I can pass the main object by reference. Note the changes to newProjectForm below.

class newProjectForm {
  var $main;
  function __construct(&$main_passed)
  {
    $this->main =& $main_passed;
  }
} 
?>

[NogDog]

bretticus wrote:

...However, the proper way to do this is to extend main....

I would take some exception to that. It's valid if the class doing the extending represents a specialized instance of the parent class (i.e. "class Student extends Person"), but it is not if the other class is a different sort of "thing" and is simply using the other object to implement its own functionality. In the latter case, by passing the "used" object to the user's constructor, you can allow for different "flavors" of the used object to be passed into the user.

class UseMe {
}

class UseMeToo Extends UseMe {
}

class User {
   var $useMe;
   public function __construct(useMe $useMe)
   {
      $this->useMe = $useMe;
   }
}

// use the original useMe:
$user1 = new User(new UseMe());

// use the variant of useMe:
$user2 = new User(new UseMeToo());

Note that since UseMeToo extends UseMe, it is considered to be both of the UseMe type as well as UseMeToo type, thus allowing us to use a type-hint of "UseMe" in the constructor and still accept either type of object.

[bretticus]

Understood,

However, it appears in this instance that "main" may be a generic base class with basic functionality that becomes extended by higher level classes. This breaks the "what kind of animal" rule of OOP, but he (or she) did say...

I want to be able to access all of the contents and functionality

Which, if my assumption is correct, extending would be the proper way to go about this. I have seen "professional" code examples posted even in other languages (like extending the Page class in .NET to assimilate the same features in a higher level class for brevity.)

[NogDog]

bretticus wrote:

Keep in mind, in the following code, if you end up merely passing a newly instantiated main to your newProjectForm, you will simply be cloning the main.

...

However, I can pass the main object by reference. Note the changes to newProjectForm below.

...

As objects are automatically passed by reference in PHP5, I'm not sure what, if anything, this gains you? Can you explain, or were you assuming PHP4?

[bretticus]

NogDog wrote:

Can you explain, or were you assuming PHP4?

I might be "borrowing" this from PHP4. However, I haved used it in PHP5 for some reason. Now I assume (knowing me, because I know me 😃 ) that I wouldn't have done that unless it was necessary (ie. if I destroy/alter $main outside of $newProjectForm $main get's altered/destroyed in $newProjectForm too.) But perhaps I am doing it from habit.

NogDog wrote:

As objects are automatically passed by reference in PHP5, I'm not sure what, if anything, this gains you?

As I have no idea what his classes do, it was a precautionary tip in case he (or she) needed to pass the object by references (however, seemingly unnecessary with PHP5.)

[NogDog]

OK, between the two of us then, we almost have one OOP expert. :p

[bretticus]

NogDog wrote:

OK, between the two of us then, we almost have one OOP expert. :p

me:10% you:90% 😃

[lazzerous]

Thanks for the insight, guys - I really appreciate it.

Here's what I ended up going with:

From withing class projects:

function newpage(){
	include_once "classes/class.newProject.php";
	$newProjectForm = new newProjectForm($this->main, '');
	echo $newProjectForm->returnOutput();
}

From the construct function of the newProjectForm class:

public function __construct(&$main, $request_vars)
	{
		$this->main = &$main;

This worked like a charm

Thanks again,
-=Lazz=-