# Re: class local instance variable

**URL:** <https://www.ruby-forum.com/t/re-class-local-instance-variable/85838>\
**Category:** Development\
**Created:** [February 16, 2007, 6:19pm UTC](https://www.ruby-forum.com/t/re-class-local-instance-variable/85838 "2007-02-16T18:19:38Z")\
**Posts on this page:** 4\
**Page:** 1

<div class="post-metadata">

**Author:** ![Park\_Ji-In](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/p/50afbb/32.png) [@Park\_Ji-In](https://www.ruby-forum.com/u/Park_Ji-In)\
**Post date:** [February 16, 2007, 6:19pm UTC](https://www.ruby-forum.com/t/re-class-local-instance-variable/85838/1 "2007-02-16T18:19:38Z")

</div>

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mithrandir@losrorien ~/ruby/ruby-svn/trunk $ cat test2.rb  
class Merong  
def m  
@ **y** = “Yes!”  
end

end

m = Merong.new  
m.m  
m.instance\_eval { @ **x** = “Yes!” }  
puts m.instance\_variables.inspect

mithrandir@losrorien ~/ruby/ruby-svn/trunk $ ./miniruby test2.rb  
[:@ **x** /#\<Class:#Merong:0xb7ed95c4\>, :@ **y** /Merong]

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---

<div class="post-metadata">

**Author:** ![Park\_Ji-In](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/p/50afbb/32.png) [@Park\_Ji-In](https://www.ruby-forum.com/u/Park_Ji-In)\
**Post date:** [February 17, 2007, 3:00am UTC](https://www.ruby-forum.com/t/re-class-local-instance-variable/85838/2 "2007-02-17T03:00:38Z")

</div>

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At Sat, 17 Feb 2007 02:18:00 +0900,  
Park Ji-In wrote in [ruby-dev:30363]:

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---

<div class="post-metadata">

**Author:** ![Park\_Ji-In](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/p/50afbb/32.png) [@Park\_Ji-In](https://www.ruby-forum.com/u/Park_Ji-In)\
**Post date:** [February 17, 2007, 7:09am UTC](https://www.ruby-forum.com/t/re-class-local-instance-variable/85838/3 "2007-02-17T07:09:49Z")

</div>

はじめまして。いなだと申します。

insntance\_eval  
の方は調べてないんですが、特異クラスで定義されたメソッドから、クラスローカルインスタンス変数が見えません。サンプルコードを添付しておきました。1.9.02007-02-16  
で動作確認しています。

オブジェクト独自のメソッドである特異メソッドは、オブジェクトのインスタンス変数のすべてにアクセスできるべきであるというのが正しいなら、クラスローカルインスタンス変数へもアクセスできるべきです。  
一方で、「クラスローカル」を字義どおりに解釈するなら、特異メソッドはオブジェクトの一部とはみなせてもクラスの一部とは見なせないので、クラスローカルインスタンス変数にアクセスできないというのも理屈です。  
この二つは両立しないんですが、どちらの解釈が正しいんでしょうか？個人的には前者の方が直感的で好みです。

class C  
def initialize  
@\_ccc = 47  
end  
def f  
@\_ccc  
end  
end

a = C.new

class \<\< a  
def g  
@\_ccc  
end  
end

p a.f # \<-- 47  
p a.g # \<-- nil

---

<div class="post-metadata">

**Author:** ![Park\_Ji-In](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/p/50afbb/32.png) [@Park\_Ji-In](https://www.ruby-forum.com/u/Park_Ji-In)\
**Post date:** [February 17, 2007, 11:27am UTC](https://www.ruby-forum.com/t/re-class-local-instance-variable/85838/4 "2007-02-17T11:27:05Z")

</div>

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In message “Re: [ruby-dev:30368] Re: class local instance variable”  
on Sat, 17 Feb 2007 15:08:57 +0900, “Makoto Inada”  
[removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid) writes:

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```
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```