[ruby-core:106084] [Ruby master Feature#18273] Class#subclasses

Issue #18273 has been updated by mame (Yusuke Endoh).


mame (Yusuke Endoh) wrote in #note-8:
> sawa (Tsuyoshi Sawada) wrote in #note-7:
> > Was the method name `Class#superclass` appropriate?
> 
> I think we don't say "C is a superclass of E" in the same situation, but I'm unsure.

Ah, I misunderstood. I have no idea whether an alias `Class#parent` is needed.

----------------------------------------
Feature #18273: Class#subclasses
https://bugs.ruby-lang.org/issues/18273#change-94673

* Author: byroot (Jean Boussier)
* Status: Open
* Priority: Normal
----------------------------------------
Ref: https://github.com/rails/rails/pull/43481

Something we forgot to mention in [Feature #14394], is either a parameter or another method to only get direct descendants.

Active Support has been offering `Class.subclasses` as:

```ruby
  def subclasses
    descendants.select { |descendant| descendant.superclass == self }
  end
```

It seems a bit silly to grab all descendants and then restrict the list when `Class#descendants` had to do some recursion to get them all in the first place.

### Proposal

We could either implement `Class#subclasses` directly, or accept a parameter in `Class#descendants`, e.g. `descendants(immediate = false)`.

cc @eregon



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