[ruby-core:112605] [Ruby master Feature#19450] Is there an official way to set a class name without setting a constant?

Issue #19450 has been updated by Eregon (Benoit Daloze).


ioquatix (Samuel Williams) wrote in #note-18:
> > One requirement for that is the given name should not be a valid constant name then (not start with a uppercase letter).
> 
> That's not how it works internally, there is actually a flag for anonymous/permanent name.

It's a requirement for humans to always be able to tell the difference. That flag is not exposed or shown.

> I wondered about whether your point of class name consistent was valid, but I found cases like this:

Yes, as I already mentioned in https://github.com/ruby/ruby/pull/7376#issuecomment-1445057920.
But `remove_const` or overriding a constant is very rarely used, there is a reason they are private or warn.
And in practice they aren't used much, so (the original) `Module#name` does reflect in 99+% how to access a named module, and that is valuable.
This feature hurts that, and `Module#name` is now possibly a "random user-supplied value" or worse a "looks like a constant path but is fake and was never assigned" (the latter one can be addressed by the requirement above).

---

I don't get why you want to show the file path in Module#name, this information is already available in the backtrace and in fact is more precise in the backtrace:
```
Module.new do
  self::C = Class.new
  c = self::C.new
  c.foo
end
---
t.rb:4:in `block in <main>': undefined method `foo' for #<#<Module:0x00007f735567e880>::C:0x00007f73673fa1b0> (NoMethodError)

  c.foo
   ^^^^
	from t.rb:1:in `initialize'
	from t.rb:1:in `new'
	from t.rb:1:in `<main>'
```
How is `#<t.rb::C:0x00007f73673fa1b0>` more useful? (it might look better to you, but what is the actual usefulness of it?)
The relevant information here is `t.rb:4` which is already there.
I have the feeling you hate the notation `#<#<Module:0x1234>::C:0x5678>`, which yes that's a bit cryptic, but it's missing the point this is hardly relevant in an exception such as the one above.

For the example in https://bugs.ruby-lang.org/issues/19450#note-6 you can just define `inspect` as an instance method of that class and be done with it.
You can customize `inspect` on the class itself like Rails does if you think people will do a lot of `p self.class` in `sus` or so.

In other words, a module name and a file path are separate things.

----------------------------------------
Feature #19450: Is there an official way to set a class name without setting a constant?
https://bugs.ruby-lang.org/issues/19450#change-102052

* Author: ioquatix (Samuel Williams)
* Status: Open
* Priority: Normal
----------------------------------------
This is the best I could come up with:

```ruby
klass = Class.new

Object.const_set("Klass", klass)
Object.send(:remove_const, "Klass")

puts klass.new
# => #<Klass:0x0000000100a9d688>
```

Can we do better?

What about something like:

```ruby
Class.new(name: "Klass")
```

or

```ruby
Class.new do
  def self.name
    "Klass"
  end
end
```

etc



-- 
https://bugs.ruby-lang.org/
 ______________________________________________
 ruby-core mailing list -- [e-mail]
 To unsubscribe send an email to [e-mail]
 ruby-core info -- https://ml.ruby-lang.org/mailman3/postorius/lists/ruby-core.ml.ruby-lang.org/