From: Kristof Bastiaensen <kristof@...>
Date: 2004-08-16T22:11:13+09:00
Subject: Re: returning symbols

Hi,

On Mon, 16 Aug 2004 21:47:59 +0900, Daniel Cremer wrote:

> I want to write a method to store a list of some instance variables in an
> Array that will later be run through to access their data. Normally in
> another language I would do this by passing them by reference when I store
> them into the Array.
> 
> Using the object_id doesn't work because that's to the object the variable
> is pointing to and this may change. So, to sum it up:
> 
> Is there a way to get variables to return their symbol so you can access
> what they will be referencing in the future ?
> 
> thanks,
> Daniel

You can use the name as a string or symbol, and retrieve
the value with instance_variable_get.

> ri instance_variable_get


------------------------------------------- Object#instance_variable_get
     obj.instance_variable_get(symbol)    => obj
------------------------------------------------------------------------
     Returns the value of the given instance variable (or throws a 
     NameError exception). The @ part of the variable name should be 
     included for regular instance variables

        class Fred
          def initialize(p1, p2)
            @a, @b = p1, p2
          end
        end
        fred = Fred.new('cat', 99)
        fred.instance_variable_get(:@a)    #=> "cat"
        fred.instance_variable_get("@b")   #=> 99

Cheers,
KB