Multiple simultaneous subscriptions are go.

lib/announcer.rb

@@ -56,12 +56,20 @@ def initialize
     @subscribers = Hash.new {|h,k| h[k] = ActionSequence.new}
   end
 
-  def subscribe(announcement_class, callable = nil, &block)
-    unless announcement_class.is_a?(Class) && announcement_class <= Announcement
-      raise TypeError, "#{announcement_class.inspect} must be an Announcement"
+  def subscribe(*args, &block)
+    unless block_given?
+      callable = args.pop
     end
 
-    @subscribers[announcement_class] << make_actions(callable || block)
+    args.each do |each|
+      unless each.is_a?(Class) && each <= Announcement 
+        raise TypeError, "#{each.inspect} must be an Announcement"
+      end
+    end
+
+    args.each do |each|
+      @subscribers[each] << make_actions(callable || block)
+    end
   end
 
   def unsubscribe(context)
@@ -77,7 +85,7 @@ def unsubscribe_from(*args)
       @subscribers[each.to_announcement.class].delete(context)
     end
   end
-
+  
   def announce(announcement)
     unless announcement.respond_to? :to_announcement
       raise TypeError, "#{announcement.inspect} must respond to \#to_announcement"

spec/ruby_announcements_spec.rb

@@ -54,6 +54,13 @@ def target
     announcer.announce Announcement
   end
 
+  it "should allow subscription to multiple announcements" do
+    target.should_receive(:got).exactly(2).times
+    announcer.subscribe(AnnouncementMockA, AnnouncementMockB) {|a| target.got(:a)}
+    announcer.announce AnnouncementMockA
+    announcer.announce AnnouncementMockB
+  end
+
   describe 'subscribing with a callable object' do
     it "should accept a lambda" do
       target.should_receive(:got_announcement).with(duck_type(:Announcement))
@@ -77,11 +84,11 @@ def target
     end
 
     it "should only accept an announcement class as an argument" do
-      lambda { announcer.subscribe(Object) {} }.should raise_error( TypeError )
+      lambda { announcer.subscribe(Object) {|| true} }.should raise_error( TypeError )
     end
 
     it "should not accept an announcement instance" do
-      lambda { announcer.subscribe(AnnouncementMockA.new) {} }.should raise_error( TypeError )
+      lambda { announcer.subscribe(AnnouncementMockA.new) {|| true} }.should raise_error( TypeError )
     end
   end