From: Austin Ziegler <halostatue@...>
Date: 2006-01-27T12:13:53+09:00
Subject: Re: Pass References To Methods As Arguments?

On 26/01/06, wegzumir <wegzumir@gmail.com> wrote:
> Hey all.  I am trying to determine the Ruby syntax for passing a
> reference to a method. I want to actually pass the reference itself as
> an argument to another method.

There is no way to do that directly in Ruby.

> Consider the following simplified Perl example. It features two
> subroutine functions and another subroutine that is capable of calling
> any subroutine passed to it as a reference.
>
>   sub print_unix_line {
>     print shift, "\n"
>   }
>
>   sub print_windows_line {
>     print shift, "\015\012";
>   }
>
>   sub call_a_routine {
>     my ($routine, $argument) = @_;
>     $routine->($argument);
>   }
>
>   &call_a_routine(\&print_unix_line, 'Hello, unix World!');
>   &call_a_routine(\&print_windows_line, 'Hello, Windows World!');

Your example really isn't a good one, but:

1.

  print_unix_line = lambda { |arg| print arg + "\n" }
  print_wind_line = lambda { |arg| print arg + "\015\012" }

  def call_a_routine(routine, argument)
    routine[argument]
    # or: routine.call(argument)
  end

  call_a_routine(print_unix_line, "Hello, unix.")
  call_a_routine(print_wind_line, "Hello, Windows.")

2.

  class Routines
    def print_unix_line(arg)
      print arg + "\n"
    end

    def print_wind_line(arg)
      print arg + "\015\012"
    end
  end

  def call_a_routine(routine, argument)
    @@routine ||= Routines.new
    @@routine.__send__(routine, argument)
  end

  call_a_routine(:print_unix_line, "Hello, unix.")
  call_a_routine(:print_wind_line, "Hello, Windows.")

As far as the poorness of the example you have, you don't need to do
anything special with Ruby to print properly:

  puts "Hello Ruby, World"

What exactly are you really trying to do?

-austin
--
Austin Ziegler * halostatue@gmail.com
               * Alternate: austin@halostatue.ca