From: Patrick Li <patrickli_2001@...>
Date: 2008-08-11T23:57:38+09:00
Subject: Bindings and Context

Hi,
I'm still really confused about Ruby Closures.

At first I thought closures are just blocks who "remember" the context
that they were defined in (so that they can refer to local variables and
methods)

And then I discovered instance_eval (which changes the context that a
block is evaluated in).

When you use instance_eval you can't call local methods anymore
(because, the scope has changed, and those methods aren't local
anymore).

But how come I can still use local variables?

    myStr = "myString"
    o = Object.new
    o.instance_eval do
      @str = myStr    # <- why does this still work?
      def method
        puts @str
      end
    end

So are local variables sort of an exception to instance_eval? And in the
above example, how come it won't work anymore if I change myStr into an
instance variable @myStr?

Thanks a lot for helping
  -Patrick

PS: Is there a detailed document I can read about OO languages? I come
from Java and I'm feeling a little lost amidst all these advanced OO
features.
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