Issue #21375 has been updated by knu (Akinori MUSHA). I'm leaning toward making Set subclass-friendly again. That's how I've always wanted Set to be (unlike Array and Hash), and the feedback shows that there are real users and use cases that share and rely on this concept, so we shouldn't easily compromise that core value. https://bugs.ruby-lang.org/issues/21396#note-8 ---------------------------------------- Bug #21375: Set[] does not call #initialize https://bugs.ruby-lang.org/issues/21375#change-113962 * Author: Ethan (Ethan -) * Status: Open * ruby -v: ruby 3.5.0dev (2025-05-26T17:42:35Z master 909a0daab6) +PRISM [x86_64-darwin22] * Backport: 3.2: UNKNOWN, 3.3: UNKNOWN, 3.4: UNKNOWN ---------------------------------------- I have a subclass of Set that overrides #initialize. Following #21216, .new does call #initialize but .[] does not. ```ruby class MySet < Set def initialize(enum = nil) compare_by_identity super end end MySet.new.compare_by_identity? # => true MySet[].compare_by_identity? # => false ``` -- https://bugs.ruby-lang.org/