From: Robert Dober <robert.dober@...>
Date: 2007-06-30T20:51:07+09:00
Subject: Re: question: referencing a variable with a variable

On 6/13/07, knohr <just_a_techie200x@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.
>
> 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}
Sorry if I am asking something stupid here but my $perl ;) days are
long gone now.
You are matching the reference of a sub with a rgexp and then call the
sub you are holding the reference of???

Assuming that you meant something like
   if (whatever) {&$choice}
you will write
   if whatever choice.call

The interesting difference will be the call of my_sub, which I have to
call my_def in Ruby ;).

def my_def callable

#now callable could be a lambda
my_def lambda{ puts 42 }
#a method
s="*" * 42
m = s.method(:size)
my_def m

But very probably you want to use something more Rubish.
def my_def ...
    yield if something # with many variations available
    Proc.new.call if something

The next approach -- my preferred -- will give you a reference to the
block - a little bit like an anonymous sub in perl.

def my_def ..., &blk
    blk.call if something
end
>
> example 2:
>
> $this = 'var_name';
> $var_name = 'i want this to print';
> print $$var_name . "\n";
>
> thanks
this = "var_name"
var_name = "I want #{this} to print"
puts var_name

 I am aware of the conceptional difference -- and that was nicely
explained already :) - but maybe that is all you need ;)

HTH
Robert
-- 
I always knew that one day Smalltalk would replace Java.
I just didn't know it would be called Ruby
-- Kent Beck