[ruby-core:92852] [Ruby trunk Feature#15725] Proposal: Add Array#reverse_sort, #revert_sort!, #reverse_sort_by, and #reverse_sort_by!

Issue #15725 has been updated by sikachu (Prem Sichanugrist).


Thank you for your initial feedback. I would like to quote one thing:

> I myself usually use .sort and .sort_by, and then apply .reverse afterwards.

That's definitely the reason why I submit this proposal, because `array.sort.reverse` will actually create new Array twice, meanwhile `reverse!` will just flip the array in-place and is a better way memory-wise. These methods will suggest programmers the most efficient way to do thing when they want to sort and reverse and Array, as I describe in the description of the ticket.

One alternative other than introducing these methods: I wonder if we can detect if a result of a sort operation is being passed to `reverse` right away in the chain, (e.g. detect if user is doing `array.sort.reverse`) and doing a in-place reverse instead. That seems complicated though, and I don't have enough knowledge of the interpreter to know if that sort of thing is possible.

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Feature #15725: Proposal: Add Array#reverse_sort, #revert_sort!, #reverse_sort_by, and #reverse_sort_by!
https://bugs.ruby-lang.org/issues/15725#change-78233

* Author: sikachu (Prem Sichanugrist)
* Status: Open
* Priority: Normal
* Assignee: 
* Target version: 
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Hello,

I would like to propose four new methods: `#reverse_sort`, `#revert_sort!`, `#reverse_sort_by`, and `#reverse_sort_by!` to Array.

These methods provides the most efficient way for user to get a reversed sorted array by calling `sort(_by)` then `.reverse!`.

As a language designer, I believe that we should suggest the most efficient way to perform a certain action to user. By introduce these methods, we can discourage user to use them instead of do `array.sort.reverse` or `array.sort {|a,b| b<=>a}` which are less performant.

I've looked through Redmine, and I saw that there was a proposal to introduce a similar method to Enumerable in https://bugs.ruby-lang.org/issues/8422, but was somewhat rejected due to the complication with infinite Enumerable. Given that Array is finite, I think this is the best place for these methods to be implemented.

I've attached a patch to implement these methods based on other `ary_sort` related methods. Please let me know your thought on how I could improve them to be mergeable, as I am not proficient in writing C.

I'm looking forward to hear your thoughts about this proposal. Thank you very much.

---Files--------------------------------
0001-Add-Array-reverse_sort-reverse_sort_by-methods.patch (6.29 KB)


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