From: "Luís Miguel Lourenço" <lmlourenco@...>
Date: 2005-01-11T04:51:07+09:00
Subject: [SOLUTION] LCD Numbers (#14)

Here's my solution.

There's an LCD class that accepts an array of numbers (digits) and a 
size.
It has an out attribute that can be used to set where it should output 
to.
LCD converts the digits to LCDDigit objects. Each LCDDigit represents a 
digit
in an LCD display and knows which segments should be on for it.
To output the digits the LCD goes along all 7 segments asking each
digit if it's on at that segment.

I over engineered it a bit, the digits could be represented as arrays.
Using full blown classes for them on the other hand makes it easier to 
test,
extend and reuse them. Not that there's much to test but anyway... I 
wanted
to play a bit with Ruby's Unit::Test.

I had previously sent a mail with a zip file attached but it didn't 
make it
into the mailing list. I suspect it was filtered but I do apologize if 
the same
mail shows up more than once.


require 'optparse'
require 'singleton'

class LCD
   SPC = ' '
   VS  = '|'
   HS  = '-'

   attr_accessor :out

   def initialize(digits, size)
     @digits = digits.collect { |d| LCDDigit.digit(d) }
     @size = size
     @out = $stdout
   end

   def output
     output_horiz_segs(1)
     output_vert_segs(2, 3)
     output_horiz_segs(4)
     output_vert_segs(5, 6)
     output_horiz_segs(7)
   end

  private
   def output_horiz_segs(seg)
     @digits.each do |d|
       @out << SPC << hseg(d, seg) * @size << SPC
       @out << SPC unless (@digits.last).equal? d
     end
     @out << $/
   end

   def output_vert_segs(seg1, seg2)
     @size.times do
       @digits.each do |d|
         out << vseg(d, seg1) << SPC * @size << vseg(d, seg2)
         @out << SPC unless (@digits.last).equal? d
       end
       @out << $/
     end
   end

   def hseg(digit, seg)
     digit[seg] ? HS : SPC
   end

   def vseg(digit, seg)
     digit[seg] ? VS : SPC
   end
end

# An LCD digit has 7 segments, they're numbered like this:
#   1
#  2 3
#   4
#  5 6
#   7
class LCDDigit
   # To create LCDDigit::LCDDigit0 .. LCDDigit:LCDDigit9 classes. Only 
the
   # segments that are on for each LCDDigit are different.
   def LCDDigit.create_digit_class(digit, segments_on)
     LCDDigit.class_eval <<-EOT
       class LCDDigit#{digit} < LCDDigit
         include Singleton

         def [](seg)
           case seg
           when #{segments_on.join(",")} then true
           else false end
         end
       end
       EOT
   end

   create_digit_class(0, [1,2,3,5,6,7])
   create_digit_class(1, [3,6])
   create_digit_class(2, [1,3,4,5,7])
   create_digit_class(3, [1,3,4,6,7])
   create_digit_class(4, [2,3,4,6])
   create_digit_class(5, [1,2,4,6,7])
   create_digit_class(6, [1,2,4,5,6,7])
   create_digit_class(7, [1,3,6])
   create_digit_class(8, [1,2,3,4,5,6,7])
   create_digit_class(9, [1,2,3,4,6,7])

   @@digits = [
     LCDDigit::LCDDigit0.instance, LCDDigit::LCDDigit1.instance,
     LCDDigit::LCDDigit2.instance, LCDDigit::LCDDigit3.instance,
     LCDDigit::LCDDigit4.instance, LCDDigit::LCDDigit5.instance,
     LCDDigit::LCDDigit6.instance, LCDDigit::LCDDigit7.instance,
     LCDDigit::LCDDigit8.instance, LCDDigit::LCDDigit9.instance
   ]

   def LCDDigit.digit(digit)
     raise 'Invalid digit' if digit < 0 or digit > 9
     @@digits[digit]
   end
end

if __FILE__ == $0
   size = 2
   opts = OptionParser.new
   opts.banner = "Usage: #{__FILE__} [options] <digits>"
   opts.on("-s SIZE", "Size of the display", /^\d$/) do |s|
     size = s.to_i
   end
   opts.on_tail("-h", "--help", "Show this message") do
     puts opts
     exit
   end

   opts.parse!(ARGV)
   digits = ARGV.shift

   if ARGV.size > 0 or digits !~ /^\d+$/
     puts opts
     exit
   end

   digits = digits.split('').map { |m| m.to_i }

   lcd = LCD.new(digits, size)
   lcd.output
end