Passing objects to functions in php

Question

I have a static function in an object that does some stuff and returns an object like so:

$objectA = ObjectA::getItem();

Then I have a function that makes other types of objects and returns an array of them, part of these types of objects require the $objectA, so it gets passed in like so:

$arrayOfObjectB = ObjectB::getStuff($objectA);

When constructing the $arrayOfObjectB I change a part of $objectA which will be a part of $objectB.

Something like this:

public static function getStuff($objectA)
{
    $arrayOfObjectB = array();
    foreach(...loops through some stuff)
      {

           $objectA->setSomething($variableChangedDuringLoop);
           $objectB = new ObjectB($objectA);
           $arrayOfObjectB[] = $objectB;
      }
}

what happens is that all of the $objectA->something in $arrayOfObjectB will have set to the same thing as the last item in the loop, what I would like to happen is for the $something to hold separate values set during the loop.

I could clone the objects each time during the loop and then set them, that would work. But this approach seems 'wrong'.

Asaph · Accepted Answer · 2016-11-29 17:33:46Z

1

When you pass a reference to $objectA to a function or a constructor, no copies of the object are made. If you make modifications to $objectA, you're affecting the same instance of the object as existed outside the the function (or constructor). If you want independent instances, you'll need to make a copy of the object. Something like this:

public static function getStuff($objectA)
{
    $arrayOfObjectB = array();
    foreach(...loops through some stuff)
      {
           // make a copy of $objectA
           $objectAClone = new ObjectA();
           $objectAClone->setX($objectA->getX());
           $objectAClone->setY($objectA->getY());
           ...
           $objectAClone->setSomething($variableChangedDuringLoop);
           $objectB = new ObjectB($objectAClone);
           $arrayOfObjectB[] = $objectB;
      }
}

answered Nov 29, 2016 at 17:33

Asaph

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2 Comments

user2209644 Over a year ago

I am already doing that, as i have mentioned at the end of the question, probably should have mentioned that way earlier, sorry about that. My question is basically, is there a better way of doing this than cloning objects?

Asaph Over a year ago

Nope. That's the way. Make a clone. It's not wrong. If you need a whole array filled with objects with different states, they can't all be the same instance. You'll need n independent instances for an array of size n. No way around that. If you want the code to look a little cleaner, you can extract the cloning operation into a separate method.

Evert · Accepted Answer · 2016-11-29 17:33:27Z

0

To do what you want, you need to clone your object. If it feels wrong it's probably because what you're trying to do is not really correct.

I could propose a better solution, but I need to know what you're actually doing with these values.

answered Nov 29, 2016 at 17:33

Evert

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