Easy definition of data classes with subclassing support and flexible constructor signatures.

Closely follows the interface of Ruby 3.2's Data class, but adds:

• Subclassing capability
• Mixed positional and keyword arguments
• Module-based design for including in existing classes

Use Lite::Data.define(klass, args:, kwargs:) with arrays for positional and keyword parameters. The following declaration generates a module with necessary instance methods and includes it in the target class:

class Foo
  Lite::Data.define(self, args: [:foo])
end

expect(Foo.new('FOO').foo).to eq('FOO')

The same works when extending existing data classes:

class Bar < Foo
  Lite::Data.define(self, kwargs: [:bar])
end

expect(Bar.new('FOO', bar: 'BAR').bar).to eq('BAR')

By default, new positional arguments are added at the start. Use :'*' as a placeholder to control positioning:

class Bax < Bar
  Lite::Data.define(self, args: [:'*', :bax])
end

expect(Bax.new('FOO', 'BAX', bar: 'BAR').bax).to eq('BAX')

Classes automatically receive:

• Comparison: ==, eql?, hash
• Cloning: with
• Introspection: deconstruct, deconstruct_keys, to_h

The deconstruct method returns values in order of inheritance, each class contributes its members in order of definition, positional first:

# inheritance chain: Bax < Bar < Foo
expect(Bax.new('FOO', 'BAX', bar: 'BAR').deconstruct)
  .to eq(%w[FOO BAR BAX])

This library is published under MIT license