From: Robert Klemme <shortcutter@...>
Date: 2008-09-01T21:03:56+09:00
Subject: Re: accessing instance variable

2008/9/1 Mayuresh Kathe <kathe.mayuresh@gmail.com>:
> Hello,
>
> I did the following;
> class O
>   @b = 0

You are not defining an instance variable of instances of O here but
of O itself.  In other words this @b and the @b below have nothing to
do with each other.

>   def x=(a)
>     @b = a
>   end
>  end
>
> o = O.new
> o.x = 1
>
> I then tried to access b by doing;
> c = o.b
>
> but irb gave me the following error;
> NoMethodError: undefined method `b' for #<O:0xb7aac424 @b=1>
>        from (irb):10
>        from /usr/lib/ruby/1.9.0/irb.rb:150:in `block (2 levels) in eval_input'
>        from /usr/lib/ruby/1.9.0/irb.rb:259:in `signal_status'
>        from /usr/lib/ruby/1.9.0/irb.rb:147:in `block in eval_input'
>        from /usr/lib/ruby/1.9.0/irb.rb:146:in `eval_input'
>        from /usr/lib/ruby/1.9.0/irb.rb:70:in `block in start'
>        from /usr/lib/ruby/1.9.0/irb.rb:69:in `catch'
>        from /usr/lib/ruby/1.9.0/irb.rb:69:in `start'
>        from /usr/bin/irb1.9:13:in `<main>'
>
> how do I access an instance variable if not via object.instance_variable?

Please look up the docs for attr_accessor, attr, attr_reader and attr_writer.

Kind regards

robert


-- 
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