[ruby-core:113377] [Ruby master Feature#19520] Support for `Module.new(name)` and `Class.new(superclass, name)`.

28 Apr 2023

      Issue #19520 has been updated by Dan0042 (Daniel DeLorme).

Eregon (Benoit Daloze) wrote in #note-39:
...
Why not `#<MyTemplate:0x000055e017895038 @path="path/to/file">` for an instance of MyTemplate and so no anonymous classes?
Because we want to compile the template to ruby once per process, and then use an instance for rendering:
```ruby
tplclass = MyTemplate["path/to/file"] #create class and compile 'render' method (if not already done)
str = tplclass.new.render(**locals)
```
This is a pretty common pattern for template engines.

----------------------------------------
Feature #19520: Support for `Module.new(name)` and `Class.new(superclass, name)`.
https://bugs.ruby-lang.org/issues/19520#change-102947

* 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
```

-- 
https://bugs.ruby-lang.org/