Bug #10276: nil/true/false に singleton メソッドを定義できてしまう

• Status: Rejected
• Priority: Normal
• Assignee: -
• Target version: -
• ruby -v: ruby 2.2.0dev (2014-09-21 trunk 47672) [x86_64-linux]
• Backport: 2.0.0: UNKNOWN, 2.1: UNKNOWN

[znz (Kazuhiro NISHIYAMA)]

nil/true/false が frozen object なのに singleton メソッドを定義できてしまいます。

% cat /tmp/f.rb
def d(o)
  p o.frozen?
  def o.m; end
rescue
  p [o, $!]
end
d(:sym)
d(1)
d(nil)
d(true)
d(false)
d(Object.new.freeze)
% ruby -v /tmp/f.rb
ruby 2.2.0dev (2014-09-21 trunk 47672) [x86_64-linux]
true
[:sym, #<TypeError: can't define singleton>]
true
[1, #<TypeError: can't define singleton>]
true
true
true
true
[#<Object:0x00000002706730>, #<RuntimeError: can't modify frozen object>]

[znz (Kazuhiro NISHIYAMA)]

frozen なオブジェクトに特異クラスが作成できるかどうかも統一されていないようですが、そういうものなのでしょうか?

>> RUBY_DESCRIPTION
=> "ruby 2.2.0dev (2014-09-25 trunk 47711) [x86_64-linux]"
>> class << :sym; end
TypeError: can't define singleton
        from (irb):2
        from /home/kazu/.rbenv/versions/git/bin/irb:11:in `<main>'
>> class << 1; end
TypeError: can't define singleton
        from (irb):3
        from /home/kazu/.rbenv/versions/git/bin/irb:11:in `<main>'
>> class << nil; end
=> nil
>> class << Object.new.freeze; end
=> nil
>>

[akr (Akira Tanaka)]

• Status changed from Open to Feedback

開発者会議のときに、奇妙だがそういうものとしようということになった覚えがあります。

[akr (Akira Tanaka)]

• Status changed from Feedback to Rejected