Q: Strict collections intersection

[jaroslavlibal]

Hello,

is there any way how to compare collections strictly in the intersect() method?

The problem is that the in_array function used at https://github.com/DusanKasan/Knapsack/blob/master/src/collection_functions.php#L1301 causes the "Nesting level too deep - recursive dependency?" error when using a Collection of big objects.

I have been thinking about sending a PR with the third param set to true; however then I realised that it could be a big BC break for some users so I would like to ask you if you have some workaround suggestion instead, pelase.

Thanks!

[DusanKasan]

Hmm, i see. I think the solution could be to rewrite intersect so that we iterate over first 2 collections, create a temporary collection of the intersection, then repeat this over the next collection, the next and so on. This would not create a BC so it should be fine and will also lessen the memory load.

Would this solve your problem?

[jaroslavlibal]

Hello, thanks for the answer. It would probably not help as the "problem" occurs also during the intersection of two collections which contains some PhpUnit mocks of Doctrine entities.

[DusanKasan]

Sorry, i misunderstood, i thought the problem was being with large collections. In the case of large objects we could introduce a method intersectStrict(collections...) or intersectUsing(comparator, collections...).

For now however, your best bet is calling filter/reject to remove the elements that are in both collections and then checking if the result is an empty collection.

[issei-m]

I'm digressing from topic a bit, but in_array without the 3rd argument seems to be scattered in codes.
IMHO, the 3rd argument of in_array should always be true nowadays, and even if we'd pass true to them, that does not make a massive impact in the PHP7 (static-type-hinting) world.