[ruby-core:112603] [Ruby master Feature#19450] Is there an official way to set a class name without setting a constant?

Issue #19450 has been updated by ioquatix (Samuel Williams).


Here are some of the places in my own code I'd like to use such a feature:

- https://github.com/ioquatix/bake/blob/a571f0c47cc202a4b46a836b87b7383d84f74fa0/lib/bake/scope.rb#L30 - "Scope<path/to/file.rb>" 
- https://github.com/ioquatix/bake/blob/a571f0c47cc202a4b46a836b87b7383d84f74fa0/lib/bake/base.rb#L32 - "<Path/To/File>" probably makes sense.
- https://github.com/socketry/utopia/blob/7f24d503f46000076fbdeeb6e28e293c9544b37b/lib/utopia/controller.rb#LL65C29-L65C29 - probably "Controller<relative/uri/path>"
- https://github.com/ioquatix/sus/blob/65e408bad260d168701bad79b2cb905ef65435e8/lib/sus/base.rb#L43 - probably "Base<description>"
- https://github.com/ioquatix/sus/blob/65e408bad260d168701bad79b2cb905ef65435e8/lib/sus/it.rb#L11 - probably "It<path/to/file.rb:line>"

There are other systems that would benefit from this, e.g. RSpec, or any test framework which loads tests into anonymous modules, or any system that basically creates `Module.new`/`Class.new` and subsequently loads code from one or more files into them.

> But it doesn't affect Module#name and error messages, which IMO is good, so error messages don't lie about this.

I disagree, the anonymous `#<#<Class:0x00007fd0ad4b3860>::Bar:0x00007fd0ad81ec70>` names are near useless. Where did it come from? Where was it defined?

> Related, Marshal and other places use rb_mod_name() (or similar) to find the class name.

In my PR, it's still considered an anonymous class. So it can't be marshalled.

> 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.


----------------------------------------
Feature #19450: Is there an official way to set a class name without setting a constant?
https://bugs.ruby-lang.org/issues/19450#change-102050

* 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



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