From: zn@...
Date: 2014-09-27T08:34:48+00:00
Subject: [ruby-dev:48580] [ruby-trunk - Bug #10276] nil/true/false に singleton メソッドを定義できてしまう

Issue #10276 has been updated by 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
>>
~~~

----------------------------------------
Bug #10276: nil/true/false に singleton メソッドを定義できてしまう
https://bugs.ruby-lang.org/issues/10276#change-49113

* Author: Kazuhiro NISHIYAMA
* Status: Open
* Priority: Normal
* Assignee: 
* Category: core
* Target version: current: 2.2.0
* ruby -v: ruby 2.2.0dev (2014-09-21 trunk 47672) [x86_64-linux]
* Backport: 2.0.0: UNKNOWN, 2.1: UNKNOWN
----------------------------------------
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>]
~~~



-- 
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