From: "mame (Yusuke Endoh) via ruby-core" <ruby-core@...>
Date: 2025-06-05T11:00:44+00:00
Subject: [ruby-core:122451] [Ruby Bug#21384] const_added is triggered twice when using autoload

Issue #21384 has been updated by mame (Yusuke Endoh).


Briefly discussed at the dev meeting. @matz said that it was not intentional to fire the hook twice. But changing it now would be a compatibility concern, so he decided to keep the current behavior.

Conceptually, we may consider this behavior as:

* When `autoload` is set, the constant is (virtually) defined (and `const_added` fires)
* When the constant is actually defined by the firing of autoload, the constant is conceptually deleted once and defined again (and `const_added` fires again)

----------------------------------------
Bug #21384: const_added is triggered twice when using autoload
https://bugs.ruby-lang.org/issues/21384#change-113632

* Author: petekinnecom (Pete Kinnecom)
* Status: Closed
* Backport: 3.2: UNKNOWN, 3.3: UNKNOWN, 3.4: UNKNOWN
----------------------------------------
As the title says, I've noticed that `const_added` is invoked twice when using `autoload`. I'm wondering if this behavior is intended or perhaps a bug. Here's a small script to reproduce what I'm seeing:


``` ruby
require "tmpdir"

dir = Dir.mktmpdir

File.write(
  File.join(dir, "const.rb"),
  "class Const; end"
)

def Object.const_added(const_name)
  super.tap { puts "const_added: #{const_name}" }
end

$LOAD_PATH << dir

puts "before autoload call"
autoload :Const, "const"
puts "after autoload call"
puts Const

# Produces output:
#
# => before autoload call
# => const_added: Const
# => after autoload call
# => const_added: Const
# => Const
```




I'm seeing the behavior using the following docker containers ruby:3.2 and ruby:3.5-rc when running like so: `docker run -v ./:/home ruby:3.5-rc ruby /home/script.rb`. Thanks.




-- 
https://bugs.ruby-lang.org/
______________________________________________
 ruby-core mailing list -- ruby-core@ml.ruby-lang.org
 To unsubscribe send an email to ruby-core-leave@ml.ruby-lang.org
 ruby-core info -- https://ml.ruby-lang.org/mailman3/lists/ruby-core.ml.ruby-lang.org/