Using 'method_missing' to reduce the code base

lib/spotify.rb

@@ -6,30 +6,38 @@
 class Spotify
   attr_writer :url
 
-  def songs
-    return @songs if @songs
-
-    @songs = []; content["tracks"].each do |song|
-      song = SpotifyContainer::Song.new(song)      
-      @songs << song if song.valid?
-    end
+  def initialize
+    @methods = {
+      :artists => {
+        :selector => :artists,
+        :class => SpotifyContainer::Artist
+      }, 
+      :songs => {
+        :selector => :tracks,
+        :class => SpotifyContainer::Song
+      }
+    }
 
-    @songs
+    @cache = {}
   end
 
-  def artists
-    return @artists if @artists
-
-    @artists = []; content["artists"].each do |artist|
-      artist = SpotifyContainer::Artist.new(artist)      
-      @artists << artist if artist.valid?
-    end
-
-    @artists
+  def method_missing(method, *args, &block)
+    @methods.keys.include?(method) ? scrape(method.to_sym) : super(method, *args, &block)
   end
 
   private
 
+    def scrape(type)
+      return @cache[type] if @cache[type]
+
+      @cache[type] = []; content[@methods[type][:selector].to_s].each do |item|
+        item = @methods[type][:class].new(item) 
+        @cache[type] << @cache[type] if item.valid?
+      end
+
+      @cache[type]
+    end
+
     def content
       @content ||= JSON.parse(download)
     end

spec/spotify_spec.rb

@@ -16,7 +16,7 @@
 
     it "should contain the right amounts of songs" do
       set_up(100, true)
-      @spotify.should have(100).songs
+      @spotify.songs.count.should eq(100)
     end
 
     it "should call SpotifyContainer::Song with the right arguments" do
@@ -40,7 +40,7 @@
 
     it "should not have any songs if nothing is valid" do
       set_up(100, false)
-      @spotify.should have(0).songs
+      @spotify.songs.count.should eq(0)
     end
   end
 
@@ -56,7 +56,7 @@
     end
 
     it "should contain the right amounts of songs" do
-      @spotify.should have(100).artists
+      @spotify.artists.count.should eq(100)
     end
 
     it "should call SpotifyContainer::Artist with the right arguments" do
@@ -77,7 +77,7 @@
 
     it "should not have any songs if nothing is valid" do
       set_up(100, false, SpotifyContainer::Artist)
-      @spotify.should have(0).artists
+      @spotify.artists.count.should eq(0)
     end
   end