Restored test/unit

git-svn-id: http://svn.ruby-lang.org/repos/ruby/trunk@19739 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

1 files changed, 90 insertions, 0 deletions

diff --git a/lib/test/unit/util/observable.rb b/lib/test/unit/util/observable.rb
new file mode 100644
index 000000000..924c10f24
--- /dev/null
+++ b/lib/test/unit/util/observable.rb
@@ -0,0 +1,90 @@
+#--
+#
+# Author:: Nathaniel Talbott.
+# Copyright:: Copyright (c) 2000-2002 Nathaniel Talbott. All rights reserved.
+# License:: Ruby license.
+
+require 'test/unit/util/procwrapper'
+
+module Test
+  module Unit
+    module Util # :nodoc:
+
+      # This is a utility class that allows anything mixing
+      # it in to notify a set of listeners about interesting
+      # events.
+      module Observable
+        # We use this for defaults since nil might mean something
+        NOTHING = "NOTHING/#{__id__}"
+
+        # Adds the passed proc as a listener on the
+        # channel indicated by channel_name. listener_key
+        # is used to remove the listener later; if none is
+        # specified, the proc itself is used.
+        #
+        # Whatever is used as the listener_key is
+        # returned, making it very easy to use the proc
+        # itself as the listener_key:
+        #
+        #  listener = add_listener("Channel") { ... }
+        #  remove_listener("Channel", listener)
+        def add_listener(channel_name, listener_key=NOTHING, &listener) # :yields: value
+          unless(block_given?)
+            raise ArgumentError.new("No callback was passed as a listener")
+          end
+      
+          key = listener_key
+          if (listener_key == NOTHING)
+            listener_key = listener
+            key = ProcWrapper.new(listener)
+          end
+      
+          channels[channel_name] ||= {}
+          channels[channel_name][key] = listener
+          return listener_key
+        end
+
+        # Removes the listener indicated by listener_key
+        # from the channel indicated by
+        # channel_name. Returns the registered proc, or
+        # nil if none was found.
+        def remove_listener(channel_name, listener_key)
+          channel = channels[channel_name]
+          return nil unless (channel)
+          key = listener_key
+          if (listener_key.instance_of?(Proc))
+            key = ProcWrapper.new(listener_key)
+          end
+          if (channel.has_key?(key))
+            return channel.delete(key)
+          end
+          return nil
+        end
+
+        # Calls all the procs registered on the channel
+        # indicated by channel_name. If value is
+        # specified, it is passed in to the procs,
+        # otherwise they are called with no arguments.
+        #
+        #--
+        #
+        # Perhaps this should be private? Would it ever
+        # make sense for an external class to call this
+        # method directly?
+        def notify_listeners(channel_name, *arguments)
+          channel = channels[channel_name]
+          return 0 unless (channel)
+          listeners = channel.values
+          listeners.each { |listener| listener.call(*arguments) }
+          return listeners.size
+        end
+
+        private
+        def channels # :nodoc:
+          @channels ||= {}
+          return @channels
+        end
+      end
+    end
+  end
+end