[DX] Unify the way the key and value are used in closures when accessing collections

[KDederichs]

Feature Request

What

First let me say I'm well aware it probably won't happen but it's been bugging me for so long now I wanted to at least mention it...

Currently when you try to operate on collections via, map, filter, findFirst etc. the closure you pass randomly has either the key or the value as first closure parameter and it's driving me nuts to always have to check which it is for the given method.

Why

Unifying it would eliminate that need to check which is the correct parameter order every time saving tons of time.

How

Optimally, you'd probably order it value first and then key for 2 reasons:

1. First I think accessing the value on those is probably more common than doing something with the key.
2. It'd probably be easier to migrate? I'm not sure if the collection interfaces are strictly used for doctrine entities, but if they are the value itself could never be some primitive type so it'd be relatively trivial to check and keep BC (?)

I'm aware this is a big change so I don't plan on this to happen anytime soon, if at all, but it would be nice...

[greg0ire]

PHP's own API is inconsistent: consider https://www.php.net/manual/en/function.array-map.php vs https://www.php.net/manual/en/function.array-filter.php

Are you saying you'd rather our API is consistent with itself, but inconsistent with the underlying PHP functions it uses? Cause I can see another universe where that's the case and maybe you complain that we are inconsistent with PHP 😛

[KDederichs]

They both seem to be using the value as first argument though? Unless I'm reading that wrong. Sure, filter uses key only in key only mode but that's to be expected.
Even in use both mode filter puts the value first according to the docs.

And array_map doesn't even pass the index as far as I can tell

[greg0ire]

Oh right, array-map and array-filter use a callback argument at a different position, but those callbacks themselves are consistent.

However as you noted this is quite a breaking change, the upgrade path does not seem easy.

[KDederichs]

Yeah that's the issue...

You could do something like check if the first argument is some kind of object (or even better if it's an doctrine entity) since I don't think those can ever be keys and then swap those around internally.

Ultimately, if it's ever going to happen I'd say it'd have to be on a Major version change as BC, since that's the only way I can think of where it'd be 100% correct in all cases.

[greg0ire]

You could do something like check if the first argument is some kind of object (or even better if it's an doctrine entity) since I don't think those can ever be keys and then swap those around internally.

Yes, I thought of that, but then it wouldn't work for collections of int or strings.