Unable to remove element from ArrayObject

Question

I have a simple class which extends ArrayObject. It looks like so:

class SimpleCollection extends ArrayObject
{

    public function __construct($arr = [])
    {
        parent::__construct($arr, ArrayObject::ARRAY_AS_PROPS);   
    }


    public function contains($value)   
    {
        return in_array($value, $this->getArrayCopy());        
    }


    public function remove($vertex)
    {
        unset($this[$vertex]);     
    }
}

Its constructor and contains method work as expected. But remove method does not work:

$arr = new SimpleCollection(['b']);

$arr->remove('b');

echo $arr->contains('b');

The last command prints true, even though I tried to remove an element form my object. What is wrong with that and how can I fix it?

And by the way, if there is a better way to check whether my simple collection contains an element (without constructing a copy of array), it would be great to know. — Jacobian
– Jacobian, Commented Feb 11, 2018 at 9:20
getArrayCopy is a method implemented in ArrayObject. It is not a custom method. — Jacobian
– Jacobian, Commented Feb 11, 2018 at 9:24
Have you enabled error reporting? Because when executing your code it throws an error at unset() for b (E_NOTICE : type 8 -- Undefined index: b) which means that you are not accessing the actual ArrayObject when trying to unset the b index. — Tom Udding
– Tom Udding, Commented Feb 11, 2018 at 9:27
@Tom Udding. I have not done that. But judging by the result this construct does not work. — Jacobian
– Jacobian, Commented Feb 11, 2018 at 9:29

Tom Udding · Accepted Answer · 2018-02-11 09:31:01Z

2

As I mentioned in my comment it throws an error at the unset() function because index b is not defined. If we take a look at var_dump($arr) this makes sense:

object(SimpleCollection)#1 (1) { 
    ["storage":"ArrayObject":private] => array(1) {
        [0]=> string(1) "b" 
    }
}

When you do $arr = new SimpleCollection(['b']); it doesn't make b the index, it makes b the value with an index of 0.

Which also makes sense because ['b'] is

array(1) { 
    [0]=> string(1) "b"
}

To get the desired result you'll have to change ['b'] to something like ['b' => 'something']. Then the remove() function will work.

answered Feb 11, 2018 at 9:31

Tom Udding

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