From: clpoda@...
Date: 2001-07-25T15:34:35+09:00
Subject: [ruby-talk:18510] Basic OO Tutorial, Ruby & Perl

I have prepared a document called rubyboot,
based on the perlboot man page (Beginner's
Object-Oriented Tutorial).  I added Ruby code
to match the function of the Perl code in various
sections of the original document.

Rubyboot is now listed on the Ruby App Archive
(under Documentation/Tutorial).

The first draft is complete, and I'd appreciate
any review comments to make it more accurate
and correct.  Find an html copy of the doc at:
http://rubyboot.sourceforge.net


One section that was a problem to me is listed
below, along with my translation from Perl to Ruby.
Please let me know if I have missed something
important, or if there are more accurate ways
to translate the Perl code to Ruby.

This code is in the section titled
'Making a method work with either classes or instances'.


##### Start Perl code

  { package Animal;
    sub speak {
      my $either = shift;
      print $either->name, " goes ", $either->sound, "\n";
    }
    sub name {
      my $either = shift;
      ref $either
        ? $$either # it's an instance, return name
        : "an unnamed $either"; # it's a class, return generic
    }
      sub named {
        my $class = shift;
        my $name = shift;
        bless \$name, $class;
      }
  }
  { package Horse;
    @ISA = qw(Animal);
    sub sound { "neigh" }
  }

## Now what happens if we invoke C<speak> on an instance?


  my $talking = Horse->named("Mr. Ed");
  print Horse->name, "\n"; # prints "an unnamed Horse\n"
  print $talking->name, "\n"; # prints "Mr Ed.\n"

  $talking->speak;  ## prints "Mr. Ed goes neigh"

##### Finish Perl code

##### Start Ruby code

 # One way to handle the case where no 'name' is provided

 class Animal
   def initialize(name)
     if name == ""
       @name = "an unnamed #{self.class} "
     else
       @name = name
     end
   end

   def speak
     print @name, " says ", sound, "\n"
   end
 end

 class Horse < Animal
   def sound; "neigh";  end
 end


 aHorse = Horse.new("")
 aHorse.speak

 talking = Horse.new("Mr. Ed")
 talking.speak


##### Finish Ruby


Thanks for the help.
clpoda