[ruby-core:109114] [Ruby master Feature#17753] Add Module#namespace

Issue #17753 has been updated by sawa (Tsuyoshi Sawada).


@ioquatix (Samuel Williams)

The non-negative part of your code looks pretty much convoluted. To simplify your code (and define it on `Module` rather than on `Class`), it would be essentially this:

```ruby
Module.prepend(Module.new do
  def name(offset = nil)
    return super() unless offset

    super().split('::').then do |parts|
      if offset >= 0
        parts.last(offset + 1)
      else
        parts[...offset]
      end
    end.join('::')
  end
end)
```

This indicates that you are essentially using the argument `offset`:

* to specify the **number** of elements when `offset` is non-negative, and
* to specify the ending **position** (index) of the elements otherwise.

which is incoherent. At least to me, your proposal is in fact difficult to understand because of this. I think it should be unified so that either `offset` expresses the number all the way down, or it does the position all the way down.


----------------------------------------
Feature #17753: Add Module#namespace
https://bugs.ruby-lang.org/issues/17753#change-98260

* Author: tenderlovemaking (Aaron Patterson)
* Status: Open
* Priority: Normal
----------------------------------------
Given code like this:

```ruby
module A
  module B
    class C; end
    class D; end
  end
end
```

We can get from `C` to `B` like `C.outer_scope`, or to `A` like
`C.outer_scope.outer_scope`.

I want to use this in cases where I don't know the outer scope, but I
want to find constants that are "siblings" of a constant.  For example,
I can do `A::B::C.outer_scope.constants` to find the list of "sibling"
constants to `C`.  I want to use this feature when walking objects and
introspecting.  For example:

```ruby
ObjectSpace.each_object(Class) do |k|
  p siblings: k.outer_scope.constants
end
```

I've attached a patch that implements this feature, and there is a pull request on GitHub [here](https://github.com/ruby/ruby/pull/4326).

---Files--------------------------------
0001-Add-Module-outer_scope.patch (5.93 KB)
0001-Add-Module-namespace.patch (5.89 KB)


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