From: pharrington <xenogenesis@...>
Date: 2009-11-29T04:30:05+09:00
Subject: Re: Local variables can't be accessed from outside, right?

On Nov 28, 1:15 pm, Michael Winterstein <parzi...@mindspring.com>
wrote:
> Benoit Daloze wrote:
>
> > I didn't find other way to get the result of class A ... end like a if
> > or
> > case result.
> > Very weared a class' instance variable(1)
> > Does it have any interest?
>
> No, it's just an example for learning about metaprogramming.  Which is
> why it seems strange; the local variables can only be 'accessed' because
> they happen to be return values.
>
> I did learn something I didn't know, however :
>
> class A
>     puts "Local variables: #{local_variables}"
>     puts "Instance variables: #{instance_variables}"
>     a = 5
>     @a = 6
>     puts "Local variables: #{local_variables}"
>     puts "Instance variables: #{instance_variables}"
> end
>
> Local variables: a
> Instance variables:
> Local variables: a
> Instance variables: @a
>
> So local variables exist in some ethereal void after the code is scanned
> but before they can be used; not so with instance variables.  That makes
> some sense.  But this also lets you do this eval weirdness.
>
From what I understand, this is because local variables are created
when code is *parsed*, not actually run (as method resolution would be
even more painful if the interpreter had to first search the object
tree for a particular instance method every time a new local variable
was defined)