Issue #19079 has been updated by jonathanhefner (Jonathan Hefner). This issue occurred for a private module in Rails: https://github.com/rails/rails/pull/46189#discussion_r991440668. Using `include` in a subclass works. Using `prepend` also works, and is the workaround I used for the Rails module. However, my proposed solution for this issue (https://github.com/ruby/delegate/pull/14) also solves #19079 with a performance improvement. I opened this issue and #19079 because the current behavior seemed surprising to me. In particular, I expected the `DelegateClass` block to behave just like a `Class.new` block. I feel like that is a reasonable assumption based on [the documentation](https://github.com/ruby/delegate/blob/2e1272cadbf86a02a0084d03e336368556f025...). But, if my assumption is wrong, then I understand the decision. ---------------------------------------- Bug #19079: Modules included in a DelegateClass cannot override delegate methods https://bugs.ruby-lang.org/issues/19079#change-100411 * Author: jonathanhefner (Jonathan Hefner) * Status: Rejected * Priority: Normal * ruby -v: ruby 3.1.2p20 * Backport: 2.7: UNKNOWN, 3.0: UNKNOWN, 3.1: UNKNOWN ---------------------------------------- Because `DelegateClass` defines delegate methods on the class itself, those delegate methods come first in the method lookup chain. This prevents included modules from overriding delegate methods: ```ruby Base = Class.new do def foo "base" end end Helper = Module.new do def foo "helper" end end WithHelper = DelegateClass(Base) { include Helper } WithHelper.new(Base.new).foo # => "base" ``` One possible solution would be to define the delegate methods in a separate module. That way, other modules could come before it in the method lookup chain. -- https://bugs.ruby-lang.org/