[ruby-core:103417] [Ruby master Feature#17753] Add Module#namespace

[fxn@hashref.com]

Issue #17753 has been updated by fxn (Xavier Noria).


> It's also a way to inform the user where that constant lives. The contents of the string have meaning.

The numerous people that have had to deal with stale objects in Rails for years know that is not entirely true. The class objects have a name, but that constant path no longer gives you the object at hand, but some another object that happens to have the same name.

Benoit, but a programming language is a formal system. It has to define things that are consistent with its model! It does not matter in my view if the examples are statistically rare. They are only ways to demonstrate the definition does not match the way Ruby works.

> A module is a namespace of constants.

Yes, but it is dynamic because of const_set and remove_const, and your APIs and concepts need to reflect that.

If you wanted namespaces, you'd have a different programming language where everything is consistent with that concept. But Ruby is not that way.

Same way Ruby does not have types. Admin::User is not a type (we all in this thread know that), it is a constant path. That is all you got, constants and objects, and constants API.

----------------------------------------
Feature #17753: Add Module#namespace
https://bugs.ruby-lang.org/issues/17753#change-91508

* 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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