Clarification on the return type of Collection::getKeys() and Collection::getValues()

[weirdan]

collections/lib/Doctrine/Common/Collections/Collection.php

Lines 118 to 136 in a4504c7

	/**
	* Gets all keys/indices of the collection.
	*
	* @return array<int, int|string> The keys/indices of the collection, in the order of the corresponding
	* elements in the collection.
	*
	* @psalm-return TKey[]
	*/
	public function getKeys() : array;
	/**
	* Gets all values of the collection.
	*
	* @return array The values of all elements in the collection, in the order they
	* appear in the collection.
	*
	* @psalm-return T[]
	*/
	public function getValues() : array;

The above specifies that those method return T[]. However, ArrayCollection actually returns list<T> (see documentation on list type). Is it unintentional, or are implementations actually allowed to return sparse arrays from those methods?

[drupol]

Hi,

I don't see anything wrong in there.

Keep in mind that array<int, int|string> is equivalent to list<int|string> which is also equivalent to TKey[] so... for me this is good.

[someniatko]

@drupol they are not equivalent. list implies that indices go from 0 to count($list) - 1 with the step 1 (0, 1, 2, 3 ... $count -1) with no gaps and shuffling. In array there might be gaps and any order.

Example:
[ 0 => 'zero', 2 => 2 ] is a valid array<int, int|string>, but invalid list<int|string>
[ 0 => 'zero', 1 => 1 ] is both a valid array<int, int|string> and list<int|string>

There is indeed nothing "wrong" in existing annotations, but list would be more precise and therefore is better - because the retval of these methods could be used as arguments to functions type-hinted against list.

[drupol]

Ooh ! Nice catch, thanks for the clarification, I didn't know :-)