From: Markus <markus@...>
Date: 2004-10-07T08:14:44+09:00
Subject: Re: Help! Newb having trouble getting a WHY'S example to work...

     There were about five minor problems (three missing to_s's, a
scoping issue with LotteryDraw's play & @@tickets, and a redo that
should have been a recursive call.
     I tried to change the structure as little as possible, so that you
can see what I did.

    -- Markus

class LotteryTicket
    NUMERIC_RANGE = 1..25
    attr_reader :picks, :purchased
    def initialize( *picks )
        if picks.length != 3
            raise ArgumentError, "three numbers must be picked"
          elsif picks.uniq.length != 3
            raise ArgumentError, "the three picks must be different
numbers"
          elsif picks.detect { |p| not NUMERIC_RANGE === p }
            raise ArgumentError, "the three picks must be numbers
between 1 and 25."
          end
        @picks = picks
        @purchased = Time.now
        end
    end

class LotteryTicket
    def self.new_random
        new( rand( 25 ) + 1, rand( 25 ) + 1, rand( 25 ) + 1 )
        rescue ArgumentError
            new_random
        end
    end

class LotteryDraw
    @@tickets = {}
    def LotteryDraw.buy( customer, *tickets )
        unless @@tickets.has_key?( customer )
            @@tickets[customer] = []
            end
        @@tickets[customer] += tickets
        end
    end

LotteryDraw.buy 'Yal-dal-rip-sip',
LotteryTicket.new( 12, 6, 19 ),
LotteryTicket.new( 5, 1, 3 ),
LotteryTicket.new( 24, 6, 8 )

class LotteryTicket
    def score( final )
        count = 0
        final.picks.each do |note|
            count +=1 if picks.include? note
            end
        count
        end
    end

class LotteryDraw
    def self.play
        final = LotteryTicket.new_random
        winners = {}
        @@tickets.each do |buyer, ticket_list|
            ticket_list.each do |ticket|
                score = ticket.score( final )
                next if score.zero?
                winners[buyer] ||= []
                winners[buyer] << [ ticket, score ]
                end
            end
        @@tickets.clear
        winners
        end
    end
    
LotteryDraw.play.each do |winner, tickets|
    puts winner + "won on " + tickets.length.to_s + " ticket(s)!"
    tickets.each do |ticket, score|
        puts "\t" + ticket.picks.join( ', ' ) + ": " + score.to_s
        end
    end






On Wed, 2004-10-06 at 15:43, mailinglist_abe@yahoo.com wrote:
> Hey, I've been an avid reader of the Why's Poignant Guide to Ruby ever since
> I discovered it (poignantguide.net), but while the material is excellent, it
> is reduced in effectiveness because I'm reasonably certain that the writer
> doesn't run (verbatim anyway) the code that he puts in some of the
> tutorials. Namely, I'm having trouble getting a "lottery" tutorial to work,
> and I'm too much of a Newb to see easily what the problem is. When I run the
> code I get an error like so: "warning: class variable access from toplevel
> singleton method"
> 
>  
> 
> My code is below, would anyone mind please skimming it and letting me know
> what the errant code is? I appreciate it!
> 
>  
> 
> Regards, Abe
> 
>  
> 
> p.s. the code below is verbatim from the guide itself - I thought that
> perhaps I'd mistyped something and so I copied and pasted the code into
> Mondrian (the IDE I'm using)
> 
>  
> 
> class LotteryTicket
> 
>  
> 
>     NUMERIC_RANGE = 1..25
> 
>  
> 
>     attr_reader :picks, :purchased
> 
>  
> 
>     def initialize( *picks )
> 
>       if picks.length != 3
> 
>         raise ArgumentError, "three numbers must be picked" 
> 
>       elsif picks.uniq.length != 3
> 
>         raise ArgumentError, "the three picks must be different numbers" 
> 
>       elsif picks.detect { |p| not NUMERIC_RANGE === p }
> 
>         raise ArgumentError, "the three picks must be numbers between 1 and
> 25." 
> 
>       end
> 
>       @picks = picks
> 
>       @purchased = Time.now
> 
>     end
> 
>  
> 
>   end
> 
>   
> 
>   class LotteryTicket
> 
>     def self.new_random
> 
>       new( rand( 25 ) + 1, rand( 25 ) + 1, rand( 25 ) + 1 )
> 
>     rescue ArgumentError
> 
>       redo
> 
>     end
> 
>   end
> 
>   
> 
>     class LotteryDraw
> 
>     @@tickets = {}
> 
>     def LotteryDraw.buy( customer, *tickets )
> 
>       unless @@tickets.has_key?( customer )
> 
>         @@tickets[customer] = []
> 
>       end
> 
>       @@tickets[customer] += tickets
> 
>     end
> 
>   end
> 
>   
> 
>     LotteryDraw.buy 'Yal-dal-rip-sip',
> 
>       LotteryTicket.new( 12, 6, 19 ),
> 
>       LotteryTicket.new( 5, 1, 3 ),
> 
>       LotteryTicket.new( 24, 6, 8 )
> 
>       
> 
>         class LotteryTicket
> 
>     def score( final )
> 
>       count = 0
> 
>       final.picks.each do |note|
> 
>         count +=1 if picks.include? note
> 
>       end
> 
>       count
> 
>     end
> 
>   end
> 
>   
> 
>     class << LotteryDraw
> 
>     def play
> 
>       final = LotteryTicket.new_random
> 
>       winners = {}
> 
>       @@tickets.each do |buyer, ticket_list|
> 
>         ticket_list.each do |ticket|
> 
>           score = ticket.score( final )
> 
>           next if score.zero?
> 
>           winners[buyer] ||= []
> 
>           winners[buyer] << [ ticket, score ]
> 
>         end
> 
>       end
> 
>       @@tickets.clear
> 
>       winners
> 
>     end
> 
>   end
> 
>   
> 
>   LotteryDraw.play.each do |winner, tickets|
> 
>      puts winner + "won on " + tickets.length + " ticket(s)!" 
> 
>      tickets.each do |ticket, score|
> 
>        puts "\t" + ticket.picks.join( ', ' ) + ": " + score
> 
>     end
> 
>   end
>