PHP : Remove object from array

user_357314 0
Viewed 100285

What is an elegant way to remove an object from an array of objects in PHP ?

Just to be clear ..

class Data{

  private $arrObservers;

  public add(Observer $o) {  
    array_push($this->arrObservers, $o);  
  }    
  public remove(Observer $o) {  
    // I NEED THIS CODE to remove $o from $this->arrObservers
  }  

}
object arrays php
12 Answers

If you want to remove one or more objects from array of objects (using spl_object_hash to determine if objects are the same) you can use this method:

$this->arrObservers = Arr::diffObjects($this->arrObservers, [$o]);

from this library.

user_103225390

Reading the Observer pattern part of the GoF book? Here's a solution that will eliminate the need to do expensive searching to find the index of the object that you want to remove.

public function addObserver(string $aspect, string $viewIndex, Observer $view)
{   
    $this->observers[$aspect][$viewIndex] = $view;
}

public function removeObserver(string $aspect, string $viewIndex)
{
    if (!isset($this->observers[$aspect])) {
        throw new OutOfBoundsException("No such aspect ({$aspect}) of this Model exists: " . __CLASS__);
    }
    
    if (!isset($this->observers[$aspect][$viewIndex])) {
        throw new OutOfBoundsException("No such View for ({$viewIndex}) was added to the aspect ({$aspect}) of this Model:" . __CLASS__);
    }

    unset($this->observers[$aspect][$viewIndex]);
}

You can loose the "aspect" dimension if you are not using that way of keeping track of which Views are updated by specific Models.

public function addObserver(string $viewIndex, Observer $view)
{   
    $this->observers[$viewIndex] = $view;
}

public function removeObserver(string $viewIndex)
{   
    if (!isset($this->observers[$viewIndex])) {
        throw new OutOfBoundsException("No such View for ({$viewIndex}) was added to this Model:" . __CLASS__);
    }

    unset($this->observers[$viewIndex]);
}

Summary

Build in a way to find the element before assigning the object to the array. Otherwise, you will have to discover the index of the object element first.

If you have a large number of object elements (or, even more than a handful), then you may need to resort to finding the index of the object first. The PHP function array_search() is one way to start with a value, and get the index/key in return.

https://www.php.net/manual/en/function.array-search.php

Do be sure to use the strict argument when you call the function.

If the third parameter strict is set to true then the array_search() function will search for identical elements in the haystack. This means it will also perform a strict type comparison of the needle in the haystack, and objects must be the same instance.

user_24956450
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