Bug #9443: Prepended methods are skipped if calling alias

• Status: Rejected
• Assignee: -
• Target version: -
• ruby -v: 2.1.0
• Backport: 1.9.3: UNKNOWN, 2.0.0: UNKNOWN, 2.1: UNKNOWN

[bcardarella (Brian Cardarella)]

I am unsure if this is related to https://bugs.ruby-lang.org/issues/7842 as that issue specifically mentions the user of "super" which my example code does not use. Anyway, here is the test to recreate:

require 'test/unit'

module A
  def foo
    'foo2'
  end
end

class B
  def foo
    'foo1'
  end
  alias_method :bar, :foo
end

B.send(:prepend, A)

class AliasTest < Test::Unit::TestCase
  def test_no_alias
    assert_equal 'foo2', B.new.foo
  end

  def test_with_alias
    assert_equal 'foo2', B.new.bar
  end
end

test_with_alias fails and will only call the original "foo" method.

I have confirmed this on Ruby 2.0.0-p353 & 2.1.0

[nagachika (Tomoyuki Chikanaga)]

I think it's intended behavior. nobu, how do you think?

[nobu (Nobuyoshi Nakada)]

• Description updated (diff)
• Status changed from Open to Rejected

It's a spec.
Aliased methods share the body, so alias_method_chain can work.
It's not related to prepend.

[trans (Thomas Sawyer)]

alias in Ruby really means "copy method". It would be nice if there were a way to truly alias, such that the two names refer to same definition.

[nobu (Nobuyoshi Nakada)]

alias in Ruby does refer to the same definition with the original method.
Probably what you want would be Forwardable.

[duerst (Martin Dürst)]

• Subject changed from Pepended methods are skipped if calling alias to Prepended methods are skipped if calling alias