From: David Masover <ninja@...>
Date: 2009-11-28T15:47:01+09:00
Subject: Re: Local variables can't be accessed from outside, right?

On Friday 27 November 2009 11:56:43 pm Michael Winterstein wrote:
> Hi, I've been trying to figure out metaprogramming and I've mostly got
> it figured out, but in doing so I ran across this example:
> 
> class A
>   def initialize
>     @a = 11
>     @@a = 22
>     a = 33
>   end
>   @a = 1
>   @@a = 2
>   a = 3
> end
> 
> 
> This was given as a posed question (can you access all the variables)
> and a particular order of the output was given (specifically, 1 2 3 11
> 22 33).

> I think a trick like puts A.new would be a lame solution,

That actually wouldn't work, though I can see why you think it'd be lame.

Anyway, as far as I know, there are only a few ways to access a local 
variable:

You could define a= -- for example,

def a=(value)
  puts a
end

The problem is, I can't actually get this to work reliably. It really seems 
like assignment of this kind would only work if you did

self.a = 33

So, with that discarded, I don't think it's possible to get access to these 
local variables with the class as written, at least not cleanly. You could 
probably figure out (programatically) where the class is defined, and then 
parse the source.

Other than that, the only way I know of getting at local variables is through 
the binding object, which you'd have to get either from inside the code, or 
from something called from that code -- but that class doesn't seem to call 
any methods from anywhere you care about, so that doesn't work.