From: "jonathanhefner (Jonathan Hefner)" <noreply@ruby-lang.org>
To: ruby-core@ml.ruby-lang.org
Subject: [ruby-core:111132] [Ruby master Bug#19079] Modules included in a DelegateClass cannot override delegate methods
Date: Thu, 01 Dec 2022 17:19:41 +0000 (UTC) [thread overview]
Message-ID: <redmine.journal-100411.20221201171941.24242@ruby-lang.org> (raw)
In-Reply-To: redmine.issue-19079.20221023030106.24242@ruby-lang.org
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/2e1272cadbf86a02a0084d03e336368556f0259e/lib/delegate.rb#L365-L369).
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/
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prev parent reply other threads:[~2022-12-01 17:19 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-10-23 3:01 [ruby-core:110483] [Ruby master Bug#19079] Modules included in a DelegateClass cannot override delegate methods jonathanhefner (Jonathan Hefner)
2022-10-23 3:02 ` [ruby-core:110484] " jonathanhefner (Jonathan Hefner)
2022-12-01 5:11 ` [ruby-core:111104] " matz (Yukihiro Matsumoto)
2022-12-01 12:38 ` [ruby-core:111126] " matz (Yukihiro Matsumoto)
2022-12-01 14:57 ` [ruby-core:111129] " Hanmac (Hans Mackowiak)
2022-12-01 17:19 ` jonathanhefner (Jonathan Hefner) [this message]
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