Issue #21392 has been updated by austin (Austin Ziegler). You are correct (and I should have known better; I have unit tests proving this). I'm not sure if this is an IRB issue, because IRB's output always outputs `<data …>`. ``` irb(main):002> p Color::CIELAB[1,2,3] CIELAB [1.0000% 2.0000 3.0000] => #<data Color::CIELAB l=1, a=2, b=3> ``` ---------------------------------------- Bug #21392: Data classes do not allow overriding #inspect https://bugs.ruby-lang.org/issues/21392#change-113518 * Author: austin (Austin Ziegler) * Status: Feedback * ruby -v: 3.4.4 * Backport: 3.2: UNKNOWN, 3.3: UNKNOWN, 3.4: UNKNOWN ---------------------------------------- I'm preparing a new version of Color and I have decided to make all of the colour classes Data classes. However, it does not appear that `#inspect` can be overridden: ```ruby module Color CIELAB = Data.define(:l, :a, :b) do def inspect "CIELAB [%.4f%% %.4f %.4f]" % [l, a, b] end end end p Color::CIELAB[1,2,3] # Expected => CIELAB[1.000% 2.000 3.000] # Actual #<data Color::CIELAB l=10, a=-125.0, b=20.5> ``` This feels like it should be permitted. -- https://bugs.ruby-lang.org/