Module Observable
In: lib/observer.rb

Implements the Observable design pattern as a mixin so that other objects can be notified of changes in state. See observer.rb for details and an example.

Methods

add_observer   changed   changed?   count_observers   delete_observer   delete_observers   notify_observers  

Public Instance methods

add_observer(observer)

Add observer as an observer on this object. observer will now receive notifications.

[Source]

     # File lib/observer.rb, line 123
123:   def add_observer(observer)
124:     @observer_peers = [] unless defined? @observer_peers
125:     unless observer.respond_to? :update
126:       raise NoMethodError, "observer needs to respond to `update'" 
127:     end
128:     @observer_peers.push observer
129:   end
changed(state=true)

Set the changed state of this object. Notifications will be sent only if the changed state is true.

[Source]

     # File lib/observer.rb, line 161
161:   def changed(state=true)
162:     @observer_state = state
163:   end
changed?()

Query the changed state of this object.

[Source]

     # File lib/observer.rb, line 168
168:   def changed?
169:     if defined? @observer_state and @observer_state
170:       true
171:     else
172:       false
173:     end
174:   end
count_observers()

Return the number of observers associated with this object.

[Source]

     # File lib/observer.rb, line 149
149:   def count_observers
150:     if defined? @observer_peers
151:       @observer_peers.size
152:     else
153:       0
154:     end
155:   end
delete_observer(observer)

Delete observer as an observer on this object. It will no longer receive notifications.

[Source]

     # File lib/observer.rb, line 135
135:   def delete_observer(observer)
136:     @observer_peers.delete observer if defined? @observer_peers
137:   end
delete_observers()

Delete all observers associated with this object.

[Source]

     # File lib/observer.rb, line 142
142:   def delete_observers
143:     @observer_peers.clear if defined? @observer_peers
144:   end
notify_observers(*arg)

If this object‘s changed state is true, invoke the update method in each currently associated observer in turn, passing it the given arguments. The changed state is then set to false.

[Source]

     # File lib/observer.rb, line 181
181:   def notify_observers(*arg)
182:     if defined? @observer_state and @observer_state
183:       if defined? @observer_peers
184:         for i in @observer_peers.dup
185:           i.update(*arg)
186:         end
187:       end
188:       @observer_state = false
189:     end
190:   end

[Validate]