From: Robert Dober <robert.dober@...>
Date: 2011-03-28T21:26:24+09:00
Subject: Re: How to get the value of a singleton class?

On Mon, Mar 28, 2011 at 10:55 AM, Brian Candler <b.candler@pobox.com> wrote:
> Robert Dober wrote in post #989410:
<snip>
> I think it *is* a design choice, because of the local variable/method
> ambiguity.
>
> If "class" and "def" did not start a new scope, then a bareword like "x"
> *might* be a local variable within a closure. It would be extremely
> difficult to tell; you'd have to read the entire program source code
> back to the beginning of the file (assuming that 'load' and 'require'
> started a new scope, otherwise it would be completely impossible).
That is a very good point, I have used closure based programming, and
I have suffered from this.
I however think that I could have done much better than I did. I
missed some opportunities to refactor and introduce more abstraction.
From this experience I conclude that this would be a "feature" to use
with care and that care does not come as natural at first...

Now if you have long modules you will run into the same kind of
problem too. I do not think that Ruby can have a save barrier against
that.

However the parser could restrict closing over one level which could
be overcome with
constructs like this

   x=42
   class A
      x=x
      def a; x end ...


However I get lost, what *really* could be a closure, I feel, is
    class << x; .... end
as we are often in metaprogramming context here.

Cheers
Robert

>
> With the current rules, given some code like
>
>   ... lots of previous stuff
>   def foo
>     x
>   end
>
> you can tell by inspection of method foo alone that x *must* be a method
> call within foo; it's definitely not a local variable.
>
> --
> Posted via http://www.ruby-forum.com/.
>
>



-- 
The 1,000,000th fibonacci number contains '42' 2039 times; that is
almost 30 occurrences more than expected (208988 digits).
N.B. The 42nd fibonacci number does not contain '1000000' that is
almost the expected 3.0e-06 times.