From: Derek Chesterfield <dez@...>
Date: 2005-09-26T23:59:18+09:00
Subject: class_eval

Stealing someone else's recent example code, what is the difference  
between this:

> class A
>      def meth2
>           puts "I'm meth2. I try to access something I ain't  
> allowed: #{static_var}"
>      end
>      static_var = 3
>      define_method(:meth3) do
>           puts "I'm meth3. I'm allowed to access #{static_var}"
>      end
> end
> a = A.new
> a.meth3
> a.meth2

and this, which seems to do the same thing, but without the class_eval:

> class B
>      def meth2
>           puts "I'm meth2. I try to access something I ain't  
> allowed: #{static_var}"
>      end
>      class_eval do
>           static_var = 3
>           define_method(:meth3) do
>                puts "I'm meth3. I'm allowed to access #{static_var}"
>           end
>      end
> end
> b = B.new
> b.meth3
> b.meth2

In other words, what does class_eval do that I'm not understanding?!