From: "fxn (Xavier Noria) via ruby-core" <ruby-core@...>
Date: 2023-06-21T22:15:47+00:00
Subject: [ruby-core:113980] [Ruby master Feature#19742] Introduce `Module#anonymous?`

Issue #19742 has been updated by fxn (Xavier Noria).


Let me clarify the vocabulary as I see it:

And _anonymous_ module has `nil` as name: `anonymous?`

A module may have a _temporary_ name if it was never assigned to a constant that belongs to a module with a permanent name.

A module may have a _permanent_ name if it was at some point assigned to a constant in a module with a permanent name.

Please excuse the circularity, but we all know what that means. It is three concepts.

Note that permanent has nothing to do with the name being a working constant path. Permanent means what it means: there is no way the name is going to change (using public API). In that sense, I believe the proposal is not aligned with the current way things work.

Note also that "temporary" and "permanent" are qualities of the name, not the module.

My personal point of view is that any attempt to introduce "parent" concepts, or steering into coupling names and constant paths is going to leak. Because in Ruby objects and storage are decoupled. People used to have types in their language may have expectations or misconceptions, but those should be revised, Ruby does not have syntax for types.

----------------------------------------
Feature #19742: Introduce `Module#anonymous?`
https://bugs.ruby-lang.org/issues/19742#change-103638

* Author: ioquatix (Samuel Williams)
* Status: Open
* Priority: Normal
----------------------------------------
As a follow-on <from https://bugs.ruby-lang.org/issues/19521>, I'd like propose we introduce `Module#anonymous?`.

In some situations, like logging/formatting, serialisation/deserialization, debugging or meta-programming, we might like to know if a class is a proper constant or not.

However, this brings about some other issues which might need to be discussed.

After assigning a constant, then removing it, the internal state of Ruby still believes that the class name is permanent, even thought it's no longer true.

e.g.

```
m = Module.new
m.anonymous? # true

M = m
m.anonyomous # false

Object.send(:remove_const, :M)
M # uninitialized constant M (NameError)

m.anonymous? # false
```

Because RCLASS data structure is not updated after the constant is removed, internally the state still has a "permanent class name".

I want to use this proposal to discuss this issue and whether there is anything we should do about such behaviour (or even if it's desirable).

Proposed PR: https://github.com/ruby/ruby/pull/7966

cc @fxn



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