[ruby-core:116242] [Ruby master Feature#19742] Introduce `Module#anonymous?`

Issue #19742 has been updated by Eregon (Benoit Daloze). Ah BTW one line below that link we see something interesting which can be repro'd on CRuby like: ```ruby irb(main):006:0> m = Module.new => #<Module:0x00007fd24624d540> irb(main):007:0> m::C = Class.new => #<Module:0x00007fd24624d540>::C irb(main):008:0> c=m::C.new => #<#<Module:0x00007fd24624d540>::C:0x00007fd246515f20> irb(main):009:0> Marshal.dump c (irb):9:in `dump': can't dump anonymous class #<Module:0x00007fd24624d540>::C (TypeError) ``` So Ruby already calls a module/class with a temporary name as "anonymous" (yet `m::C.name` returns a String). ---------------------------------------- Feature #19742: Introduce `Module#anonymous?` https://bugs.ruby-lang.org/issues/19742#change-106263 * Author: ioquatix (Samuel Williams) * Status: Open * Priority: Normal ---------------------------------------- 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/