From: Brian Candler <B.Candler@...>
Date: 2007-05-22T21:53:18+09:00
Subject: Re: bug in ruby

On Tue, May 22, 2007 at 09:41:03PM +0900, sairam MP wrote:
> class Foo
>   attr_accessor :bar
> 
> 
>   def foo
>     self.bar = 1
> 
> 
>     if false
>       bar = 2        # never executed
>     end
> 
> 
>     p self.bar       # prints 1
>     p bar            # prints nil
>   end
> end

This is a bug in your understanding of the language, not in the language
itself. You've not said exactly what you think it *should* do instead of
what it does, so it's hard to give an answer tailored to improving your
understandly.

But briefly: an assignment like "bar = 2" is seen at the time the program is
*parsed* and means that an unqualified "bar" is treated as a local variable
from that point onwards until the end of that scope. Whether or not it is
actually *executed* makes no difference.

When you write "self.bar" or "self.bar=" you are explicitly making a method
call to a method "bar" or "bar=" on the current object; this is never
treated as a local variable.

If you write "bar" by itself, this is treated as a method call on the
current object *unless* an assignment of the form "bar = x" has been seen by
the parser earlier in the scope.

Regards,

Brian.