21 Jun
2023
21 Jun
'23
11:33 p.m.
Issue #19742 has been updated by ioquatix (Samuel Williams).
The concepts are discussed in the code, but they shouldn't be assumed as canonical,
IMHO.
```c
/**
* Returns +classpath+ of _klass_, if it is named, or +nil+ for
* anonymous +class+/+module+. A named +classpath+ may contain
* an anonymous component, but the last component is guaranteed
* to not be anonymous. <code>*permanent</code> is set to 1
* if +classpath+ has no anonymous components. There is no builtin
* Ruby level APIs that can change a permanent +classpath+.
*/
static VALUE
classname(VALUE klass, bool *permanent)
```
A class/module that is assigned a name via `set_temporary_name` may still be anonymous, so
I believe the above comment needs to be updated.
In the code, when something is not `permanent`, a `temporary` class path may be
generated:
```c
static VALUE
make_temporary_path(VALUE obj, VALUE klass)
{
VALUE path;
switch (klass) {
case Qnil:
path = rb_sprintf("#<Class:%p>", (void*)obj);
break;
case Qfalse:
path = rb_sprintf("#<Module:%p>", (void*)obj);
break;
default:
path = rb_sprintf("#<%"PRIsVALUE":%p>", klass,
(void*)obj);
break;
}
OBJ_FREEZE(path);
return path;
}
```
To clarify, the documentation states that when `mod.name == nil`, the `mod` is anonymous.
But it does not state that when `mod.name =! nil`, the module is permanent AFAICT.
In any case, we should probably clarify this in the documentation.
----------------------------------------
Feature #19742: Introduce `Module#anonymous?`
https://bugs.ruby-lang.org/issues/19742#change-103639
* 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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