From: "misaka@..." <misaka@...>
Date: 2007-06-14T20:15:03+09:00
Subject: Re: question: referencing a variable with a variable

On Jun 13, 10:26 pm, knohr <just_a_techie2...@yahoo.com> wrote:
> I come from a perl background.  I have gotten in the habit of using
> references to variables instead of specifically calling said variable/
> class/whatever.

I don't think that symbolic references directly supported in Ruby, but
as Phrogz pointed out there are certain methods to access variables
and methods by using a string representation of their name.

>
> Basically, I am wondering how I would translate the following into
> ruby.
>
> example 1:
> sub my_sub
>   {
>   $choice = shift;
>   $choices="this|that|foo|bar";
>   if ( $choice =~ m/($choices)/ ) {&$choice}
>   else {die "some witty msg"}
>   }

This one is easy, there's a "send" method that let's you call a method
using a string containing it's name. Here's an abbreviated version of
what you have above:

  def my_sub( $choice )
      if $choice =~ /foo|bar/
          send( $choice )
      end
  end


> example 2:
>
> $this = 'var_name';
> $var_name = 'i want this to print';
> print $$var_name . "\n";

Looks like this would probably need an eval:

  this = 'var_name'
  var_name = 'i want this to print'
  puts( eval( this ) )

There are methods to list local variables 'local_variables', and
return instance variables, but there isn't really anything to actually
return the value of a local variable so far as I can see.


--Misha