Issue #19278 has been updated by zverok (Victor Shepelev).
I don't really understand this example. The initialize works the same way whether you use a Struct or not
It is not. 1. Both 3.2+ `Struct` and `Data` make a promise that **no other class makes** and is **non-trivial to implement**: if you have Struct/Data-derived class `C` with member `x`, then both `C.new(x: 1)` and `C.new(1)` work. 2. These promises are implemented differently (because different people worked on them :shrug:): In `Struct`, the `#initialize` handles "unify positional and keywords", in `Data`, `.new` handles. 3. This leads to different cost/benefit outcome: in `Struct`, it is "like in other classes" but **redefining `#initialize` is non-trivial**, in `Data`, it is "one interesting quirk", but **redefining `#initialize` is trivial**. Can you please provide a small realistic example of how would you like to define your Struct or Data-inherited class' `#initialize` to **not break this contract** and achieve the goal you were trying to achieve? We can proceed from there to maybe come to some compromise or better understand each other's points. ---------------------------------------- Bug #19278: Constructing subclasses of Data with positional arguments https://bugs.ruby-lang.org/issues/19278#change-100908 * Author: tenderlovemaking (Aaron Patterson) * Status: Feedback * Priority: Normal * ruby -v: ruby 3.2.0 (2022-12-25 revision a528908271) [arm64-darwin22] * Backport: 2.7: UNKNOWN, 3.0: UNKNOWN, 3.1: UNKNOWN, 3.2: UNKNOWN ---------------------------------------- I'd expect both of the following subclasses to work, but the subclass that uses positional parameters raises an exception: ```ruby Foo = Data.define class Bar < Foo def initialize foo: p foo end end class Baz < Foo def initialize foo p foo end end Bar.new foo: 1 # Prints 1 Baz.new 1 # Raises ArgumentError ``` I'd expect the subclass that uses positional arguments to work. -- https://bugs.ruby-lang.org/