Add day three self study code and fixture

ruby/day3/playlist.csv

@@ -0,0 +1,6 @@
+Artist,Song
+Imogen Heap,Angry Angel
+Marina And The Diamonds,Are You Satisfied?
+Muse,Undisclosed Desires
+Cake,Going The Distance
+Florence And The Machine,Rabbit Heart

ruby/day3/selfstudy.rb

@@ -0,0 +1,104 @@
+# Yeah, I know I am going rogue agent here, but I don't like the idea 
+# of having to include a mixin module just to do "acts_as_XXXX"
+
+class Row
+  def initialize(mappings)
+    @mappings = mappings
+    puts @mappings.inspect
+  end
+
+  def method_missing(name, *args)
+    @mappings[name.to_s]
+  end
+
+  private
+  attr_accessor :mappings
+end
+
+module ActsAsCsv
+  def self.included(base)
+    base.extend(ClassMethods)
+  end
+
+  module ClassMethods
+    def acts_as_csv
+      attr_accessor :headers, :csv_contents
+      include(InstanceMethods)
+    end
+  end
+
+  module InstanceMethods
+    # Minor changes below *before* suggested modifications in exercise
+    def initialize
+      @csv_contents = []
+      root_dir = File.dirname(__FILE__)
+      filename = File.join(root_dir, self.class.to_s.downcase + ".csv")
+      file = File.new(filename, 'r')
+      header = true
+
+      file.each do |row|
+        if header
+          @headers = parse_headers(row)
+          header = false
+        else
+          @csv_contents << parse_data(@headers, row)
+        end
+      end
+    end
+
+    def each
+      @csv_contents.each do |row|
+        yield row
+      end
+    end
+
+    private
+    def parse_headers(headers)
+      parse_row(headers)
+    end
+
+    def parse_data(headers, data)
+      row_hash = {}
+      parse_row(data).each_with_index do |elem, idx|
+        # downcase to conform to Ruby method naming conventions
+        header_name = @headers[idx].downcase
+        row_hash[header_name] = elem
+      end
+      Row.new(row_hash)
+    end
+
+    def parse_row(row)
+      row.chomp.split(',')
+    end
+  end
+end
+
+# Any subclass of Parsable will be able to just type:
+#   +acts_as_csv+
+class Parsable
+  include ActsAsCsv
+  # We could then mixin ActsAsXml, ActsAsJson, etc. too
+  # IMHO this reads better.
+  # Alternatively instead of coding both:
+  #   +include MixinModule+
+  # and
+  #   +acts_as_XXX+
+  # it is ugly and error prone. Why not just:
+  #   +inclue MixinModule+
+  # and assume they want the behavior mixed in already?
+
+  # Not a fan of the code style shown in the book myself!:)
+end
+
+
+class Playlist < Parsable
+  acts_as_csv
+end
+
+pl = Playlist.new
+puts pl.headers.inspect
+puts pl.csv_contents.inspect
+
+pl.each do |row|
+  puts row.artist
+end