Hello David,
On Sat, 11 Nov 2023 at 20:04, David Gebler <davidgeb...@gmail.com> wrote:
>
> On Sat, Nov 11, 2023 at 6:05 PM Andreas Hennings <andr...@dqxtech.net>
> wrote:
>
> > Hello internals,
> > I noticed that array functions like array_diff(), array_intersect()
> > etc use weak comparison.
> >
> >
> That's not quite correct. Using the example of array_diff, the comparison
> is a strict equality check on a string cast of the values. So
> array_diff([""], [false]) will indeed be empty
> but array_diff(["0"],[false]) will return ["0"].
Thanks, good to know!
So in other words, it is still some kind of weak comparison, but with
different casting rules than '=='.
Still this is not desirable in many cases.
>
> Tbh any use case for whatever array function but with strict comparison is
> such an easy thing to implement in userland[1] I'm not bothered about
> supporting it in core. But that's just me. I don't generally like the idea
> of adding new array_* or str_* functions to the global namespace without
> very good cause. There is a precedent for it though, in terms of changes
> which have gone through in PHP 8, such as array_is_list or str_starts_with.
I would argue that the strict variants of these functions would be
about as useful as the non-strict ones.
Or in my opinion, they would become preferable over the old functions
for most use cases.
In other words, we could say the old/existing functions should not
have been added to the language.
(of course this does not mean we can or should remove them now)
Regarding performance, I measure something like factor 2 for a diff of
range(0, 500) minus [5], comparing array_diff() vs array_diff_strict()
as proposed here.
So for large arrays or repeated calls it does make a difference.
Regarding the cost of more native functions:
Is the concern more about polluting the global namespace, or about
adding more functions that need to be maintained?
I can see both arguments, but I don't have a clear opinion how these
costs should be weighed.
Cheers
Andreas
>
> [1] Example:
>
> function array_diff_strict(array $array1, array ...$arrays): array
> {
> $diff = [];
> foreach ($array1 as $value) {
> $found = false;
> foreach ($arrays as $array) {
> if (in_array($value, $array, true)) {
> $found = true;
> break;
> }
> }
> if (!$found) {
> $diff[] = $value;
> }
> }
> return $diff;
> }
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