[ruby-core:81301] [CommonRuby Feature#13585][Rejected] select! and reject! do not returns the same array in specific situations

Issue #13585 has been updated by duerst (Martin D端rst).

Status changed from Open to Rejected

This can be surprising, but it's in line with many other destructive methods. It can be very useful when writing a loop that continues until there's no change anymore. Avoiding destructive methods leads to a better programming style anyway, and in most cases is not slower (because internally, most destructive methods are implemented by copying the actual data (or references) anyway).

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Feature #13585: select! and reject! do not returns the same array in specific situations
https://bugs.ruby-lang.org/issues/13585#change-64975

* Author: sobrinho (Gabriel Sobrinho)
* Status: Rejected
* Priority: Normal
* Assignee: 
* Target version: 
----------------------------------------
When all elements are returned on select!, the method returns nil.

~~~
(main) normal> [1,2,3].select! { |x| x == 0 }
=> []
(main) normal> [1,2,3].select! { |x| x == 1 }
=> [1]
(main) normal> [1,2,3].select! { |x| x == 1 || x == 2 }
=> [1, 2]
(main) normal> [1,2,3].select! { |x| x == 1 || x == 2 || x == 3 }
=> nil
```

When all elements are kept on reject!, nil is returned.

~~~
(main) normal> [1,2,3].reject! { |x| x == 0 }
=> nil
(main) normal> [1,2,3].reject! { |x| x == 1 }
=> [2, 3]
(main) normal> [1,2,3].reject! { |x| x == 1 || x == 2 }
=> [3]
(main) normal> [1,2,3].reject! { |x| x == 1 || x == 2 || x == 3 }
=> []
~~~

This is surprising since it breaks code in very specific situations that most people won't notice easily:

~~~
blocked_assets = relation.to_a.select! { |asset| asset.blocked? }
unblocked_assets = relation.to_a.reject! { |asset| asset.unblocked? }
~~~



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