From: "jeremyevans0 (Jeremy Evans) via ruby-core" <ruby-core@...>
Date: 2024-05-30T16:45:00+00:00
Subject: [ruby-core:118106] [Ruby master Bug#20513] the feature of kwargs in index methods has been removed without due consideration of utility and compatibility

Issue #20513 has been updated by jeremyevans0 (Jeremy Evans).


bughit (bug hit) wrote in #note-13:
> > Yes. The change is only for []=. Some methods like Dir[] do take keyword arguments, and it's unchanged.
> 
> Someone should correct the release notes.

Agreed.  I'll take care of that.

> This asymmetry/inconsistency between `[]` and `[]=` syntax is arguably even worse. Its arbitrary and incoherent. kwargs being legal in the index reader, strengthens the argument for them being legal in the index writer.

The change is neither arbitrary nor incoherent.  Keyword arguments in aref syntax do not have the problems that keyword arguments have in aset/op_asgn/masgn syntax.  Allowing them in aref but prohibiting them in aset/op_asgn/masgn was done for good reasons already explained.

----------------------------------------
Bug #20513: the feature of kwargs in index methods has been removed without due consideration of utility and compatibility 
https://bugs.ruby-lang.org/issues/20513#change-108539

* Author: bughit (bug hit)
* Status: Closed
* Backport: 3.1: UNKNOWN, 3.2: UNKNOWN, 3.3: UNKNOWN
----------------------------------------
See #20218

The ability to pass kwargs to index methods has been in ruby for a long time, probably from the inception of kwargs, so there's code that makes use of it. Other than the multiple assignment edge-case it's been working fine and is not conceptually unsound. kwargs allow for more variability in store/lookup operations via index methods, letting you control where/how something is stored/looked up. 

this is from 2.6
```ruby
module IndexTest
  @store = {}

  def self.store
    @store
  end

  def self.key(name, namespace: nil)
    name = "#{namespace}:#{name}" if namespace
    name
  end

  def self.[](name, namespace: nil)
    p [name, namespace]
    @store[key(name, namespace: namespace)]
  end

  def self.[]=(name, opts = {}, val)
    p [name, opts, val]
    @store[key(name, namespace: opts[:namespace])] = val
  end


end

IndexTest['foo'] = 1
p IndexTest['foo']
IndexTest['foo', namespace: 'bar'] = 2
p IndexTest['foo', namespace: 'bar']
p IndexTest.store
```

A reasonable breaking change would be for `[]=` to have real kwargs, rather than the middle positional kwarg collector hash in the above example. 

I am not arguing that breaking changes can't be introduced, but that a removal of a long-standing feature deserves more consideration and deliberation than the following:

> I found that use of keyword arguments in multiple assignment is broken
> Can we also prohibit keyword arguments ... ?
> OK, prohibit keyword arguments





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