Issue #19742 has been updated by Dan0042 (Daniel DeLorme).
After reading all the above it doesn't seem like there's a clear agreement on what
this proposed `#anonymous?` is supposed to be. If it's just equivalent to `.name.nil?`
then what is the point? Else, what is the behavior exactly?
```ruby
m::A.name #=> "#<Module:0x00007f27f032d678>::A"
m::A.anonymous? #=> true or false?
M = m
m::A.name #=> "M::A"
m::A.anonymous? #=> false
Object.send(:remove_const, :M)
m::A.name #=> "M::A"
m::A.anonymous? #=> true or false?
```
And once the behavior is clarified, what is an example use case? It's very rare to use
either an anonymous namespace or remove_const, so what would you use this `#anonymous?`
method for? Some things have been mentioned like logging/formatting,
serialisation/deserialization, debugging or meta-programming, but concrete examples are
missing.
Since Ruby 3.0, Module#name can return a string like
`"#<Module:0x00007f27f032d678>::A"` whereas previously it returned nil. I
can imagine `#anonymous?` could be a way to get back the equivalent of `.name.nil?` in
Ruby 2.7. The current implementation in Rails is probably buggy since Ruby 3.0, but no one
has ever triggered the bug since no one ever uses anonymous modules.
----------------------------------------
Feature #19742: Introduce `Module#anonymous?`
https://bugs.ruby-lang.org/issues/19742#change-106259
* 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
--
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