Arrays::updateDiff()

[milo]

• new feature
• BC break? no
• doc PR: will

Proposed Arrays::updateDiff() compares two associative arrays and returns such items from later one, which does not exist or differs from first one. By other words - which items have to be updated in first array, to be the same as second array.

As far as I know, there is no PHP function for that (playground). For examle:

$from = ['a' => null];
$to = ['a' => false];

# I didn't find a PHP function which returns
$diff = ['a' => false];

There are posible things to debate:

• function name
• arguments order
• recursive version
• objects comparing
• 3rd argument callable $comparator = null

[JanTvrdik]

So it's like array_diff_assoc but with strict comparision?

[milo]

Yes. Behaviour probably same as:

return array_udiff_assoc($to, $from, function ($a, $b) {
	return $a === $b ? 0 : ($a > $b ? 1 : -1);  # spaceship cannot be used because null <=> false === 0
});

I write probably, because I'm not sure why yes/no comparator can return -1/0/1 and how result depends on it.
And the foreach loop is ~3 times faster.