Issue #19742 has been updated by fxn (Xavier Noria).
It would mean on remove_const and on const_set(name,
v) when there was already a constant name, to change the name of the old constant if it is
a module.
If I understand this correctly, I believe it is not possible preserving today's
rules.
Nowadays, if a module was ever stored in a constant that belonged to a module with a
permanent name, it has a permanent name.
In other words, today, this cannot happen:
```
A::C.anonymous? # => true, not possible
```
If a reassignment or `remove_const` changed the name of the module to temporary, you could
fall into that easily:
```
X::Y = Module.new
Z::W = X::Y
X::Y = Module.new
```
After that, `Z::W` cannot be anonymous if `Z` has a permanent name.
Let me say it again: Ruby is not Java, there are no types or type identifiers or anything.
It's all storage and objects. Chasing that a name is a constant path that resolves to
the same object is going to leak, or will need to change the language.
If a logical system does not have constraints, you won't get properties that do not
follow.
----------------------------------------
Feature #19742: Introduce `Module#anonymous?`
https://bugs.ruby-lang.org/issues/19742#change-103738
* 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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