From: Greg Weeks <greg.weeks@...>
Date: 2007-11-17T18:29:11+09:00
Subject: Re: "instance_eval" (eg, sent to a class object)

Xavier Noria wrote:
>    C = "Object"
> 
>    class String
>      C = "String"
>    end
> 
>    a = ''
>    a.instance_eval do
>      def c_in_block; C; end
>    end
> 
>    a.instance_eval <<EOS
>      def c_in_string; C; end
>    EOS
> 
>    puts a.c_in_block  # -> Object
>    puts a.c_in_string # -> String

The more that I think about scoping in the context of

    closures define_method instance_eval module_eval eval

the more confused I get.  Alas, I've never seen a formal description of
the Ruby execution model.  There seems to be a current self and a
current klass, but I don't know exactly how they are set and used.

I'll just say here that your fine example can be simplified a little:

    a.instance_eval { C }  ->  "Object"
    a.instance_eval "C"    ->  "String"
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