[ruby-core:113137] [Ruby master Feature#19520] Support for `Module.new(name)` and `Class.new(superclass, name)`.

Issue #19520 has been updated by psadauskas (Paul Sadauskas).


FWIW, I've run into a desire for this feature on two separate occasions recently. In both cases, I'm writing an HTTP Client for an API, and want to provide a nice interface to it. The products behind the APIs are very customizable, so different customers may see different fields returned by the API, and the APIs provide a "meta" API that describes the fields and types, etc... At runtime, I want to parse the output of the Meta API, and define a Ruby Class with attributes that match. Then when I consume the regular API, its easy to initialize instances of those Classes with the data.

However, since each customer of mine may have a different set of fields, and these classes may be temporary or ephemeral, I don't want to end up with a bunch of constants defined like `MyApiClient::Customer12345::Lead`, that will never get garbage collected. But, I'd still like my temporary classes to have names, since some of the libraries I'm using like Rails and Dry::Types get grumpy if given an anonymous class.

I have a slight preference towards @ioquatix's proposal #19521, but either of these will solve this particular use-case.



----------------------------------------
Feature #19520: Support for `Module.new(name)` and `Class.new(superclass, name)`.
https://bugs.ruby-lang.org/issues/19520#change-102672

* Author: ioquatix (Samuel Williams)
* Status: Open
* Priority: Normal
----------------------------------------
See <https://bugs.ruby-lang.org/issues/19450> for previous discussion and motivation.

[This proposal](https://github.com/ruby/ruby/pull/7376) introduces the `name` parameter to `Class.new` and `Module.new`:

```ruby
Class.new(superclass, name)
Module.new(name)
```

As a slight change, we could use keyword arguments instead.

## Example usage

The current Ruby test suite has code which shows the usefulness of this new method:

```ruby
  def labeled_module(name, &block)
    Module.new do
      singleton_class.class_eval {
        define_method(:to_s) {name}
        alias inspect to_s
        alias name to_s
      }
      class_eval(&block) if block
    end
  end
  module_function :labeled_module

  def labeled_class(name, superclass = Object, &block)
    Class.new(superclass) do
      singleton_class.class_eval {
        define_method(:to_s) {name}
        alias inspect to_s
        alias name to_s
      }
      class_eval(&block) if block
    end
  end
  module_function :labeled_class
```

The updated code would look like this:

```ruby
  def labeled_module(name, &block)
    Module.new(name, &block)
  end

  def labeled_class(name, superclass = Object, &block)
    Class.new(superclass, name, &block)
  end
  module_function :labeled_class
```



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