How do I access an object from inside another object?

JdS · #1 07-Jun-2003, 08:26

Let's assume my page, test.php looks a bit like this:

PHP Code:


<?php

// TEST.PHP

$one = new Orange();
$one->DoSomethingInOrange();

// ... some other code

$two = new Blue();
$two->ProcessSomethingInBlue();
?>

So far so good... now if we look in class Orange(), this is what it could look like...

PHP Code:


<?php

// ORANGE.LIB.PHP

class Orange()
{
  function Orange()
  {
    // constructor = nothing
  }

  function DoSomethingInOrange()
  {
    $this->color = 'Orange';
  }

  function ReturnAValueFromOrange()
  {
    return '"I said '.$this->color.'."';
  }
}
?>

On to Blue()...

PHP Code:


<?php
// BLUE.LIB.PHP

class Blue()
{
  function Blue()
  {
    // constructor = nothing
  }

  function ProcessSomethingInBlue()
  {
    // HERE!!! what happens if for whatever
    // reason, I want to echo
    // $one->ReturnAValueFromOrange()???

    // What I have done right now is something like this
    // but, it doesn't seem like it's very correct
    
    // if some checking fails...

    echo $GLOBALS['one']->ReturnAValueFromOrange();
  }
}

?>

I seriously hope that made sense... I can get the code to work flawlessly but I am almost certain there's something in PHP that should let me access an object method/property from within another object or not?

Allowee · #2 07-Jun-2003, 08:51

did you try to make $one a var or made it global in the function?

JdS · #3 07-Jun-2003, 08:58

I don't understand your question, I didn't make anything global, since I created that object/variable inside test.php.

Even if it were a regular variable, I would usually access it from inside a function this way: $GLOBALS['variable_name'].

I was just re-using that logic for this problem and it worked; but I am not comfortable... hence the question.

Garth Farley · #4 07-Jun-2003, 13:04

I suggest you have a look at references. I'm unfamiliar with the syntax myself, but there's a couple of good giudes around.

Essentially, you've a problem with what you've done above if you create a couple of "Orange"s objects, because with what you've done, the global will be only from the last object you instantiased.

Using a reference, you can send the Blue class a reference (like an address inside - not a copy) to the Orange object you want to look into, and then using the reference, Blue willl be allowed to look inside Orange.

I'm sorry I've not used them before, so I can't advise syntax, but they're used a lot in C++. But the PHP manual has a nice section on it.

GF

JdS · #5 08-Jun-2003, 06:48

So okay... I added a method in Blue() that will accept the other object, passed by reference. So the new class: Blue() looks like this now

PHP Code:


<?php
// BLUE.LIB.PHP

class Blue()
{
  function Blue()
  {
    // constructor = nothing
  }

  function SetOrangeObj( &$obj )
  {
    $this->OrangeObj = $obj;
  }

  function ProcessSomethingInBlue()
  {
    // HERE!!! what happens if for whatever
    // reason, I want to echo
    // $one->ReturnAValueFromOrange()???

    // Previously....
    // echo $GLOBALS['one']->ReturnAValueFromOrange();

    // now the line looks like this
    echo $this->OrangeObj->ReturnAValueFromOrange();
  }
}

?>

After I edit test.php by adding the one line for the new method in Blue():

PHP Code:


<?php
// TEST.PHP

$one = new Orange();
$one->DoSomethingInOrange();

// ... some other code

$two = new Blue();
$two->SetOrangeObj( $one ); // <-- here's the added line....
$two->ProcessSomethingInBlue();

?>

Is this what you mean? FYI, it works...

Garth Farley · #6 10-Jun-2003, 08:51

Well if it works, I must've meant it

GF

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