From: Lyle Johnson <lyle@...>
Date: 2009-11-25T04:02:58+09:00
Subject: Re: Help with each_with_index method

On Tue, Nov 24, 2009 at 12:00 PM, Chris Pelow <chris.pelow@gmail.com> wrote:

> Basically I have 5 names entered into an array. They have a firstname
> and surname. A middlename is then optional.
> What I want to do is to print out the names like this..
> John Seymour Smith
> Peter        Jones
> Mary         Walsh
>
> So it yields the middlename and prints it out if it has one.

For starters, your Person class doesn't need to mix-in Enumerable, and
it doesn't need an "each" method. The array (people) that you're
adding Person instances to is the thing that is enumerable, and it has
its own each method built-in. So a trimmed down Person class could
look like so:

    class Person
        include Comparable
        attr_accessor :firstname, :middlename, :surname

        def initialize (firstname, middlename, surname)
                @firstname = firstname
                @middlename = middlename
                @surname = surname
        end

        def to_s
                "Hello my name is #@firstname #@surname and i'm #@age"
        end

        def <=> (other)
                (self.firstname) <=> (other.firstname)
        end
    end

Your comparison method (the <=> method) isn't quite right, since it's
only comparing their first names, but I'll let you ponder how you
might improve that. You're on the right track.

Now, given your requirement for how you'd like the names to be
printed, I think I'd also add a full_name() method to the Person
class, something like:

    class Person
      def full_name
        unless middlename.empty?
          "#{firstname} #{middlename} #{surname}"
        else
          "#{firstname} #{surname}"
        end
      end
    end

Finally, there are several issues with the bit at the end where you're
trying to iterate over the array of people. You have two loops (an
#each loop and then an #each_with_index loop) nested inside each
other. For the inner loop, the "index" and "person" arguments that
each_with_index() passes into the block aren't instance variables, so
you just refer to them as "index" and "person", not "@index" and
"@person". I'd change that last bit to look like this:

    people_sorted = people.sort
    people_sorted.each_with_index do |person, index|
      puts "Hi there #{index} #{person.full_name}!"
    end

Hope this helps,

Lyle