[ruby-core:117101] [Ruby master Feature#19742] Introduce `Module#anonymous?`

Issue #19742 has been updated by fxn (Xavier Noria). Now, the name of classes and modules can be one of three things: 1. `nil` 2. Temporary 3. Permanent Maybe it would make sense to provide matching predicates, say: 1. `mod.anonymous?` 2. `mod.temporary_name?` 3. `mod.permanent_name?` so that users have an encapsulated way to check the status of the name. For example, in the Rails code base, logic like this: ```ruby @controller_path ||= name.delete_suffix("Controller").underscore unless anonymous? ``` could be rewritten as ```ruby @controller_path ||= name.delete_suffix("Controller").underscore if permanent_name? ``` What do you think? ---------------------------------------- Feature #19742: Introduce `Module#anonymous?` https://bugs.ruby-lang.org/issues/19742#change-107174 * Author: ioquatix (Samuel Williams) * Status: Open ---------------------------------------- As a follow-on <from https://bugs.ruby-lang.org/issues/19521>gt;, 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 -- https://bugs.ruby-lang.org/