Changes between Initial Version and Version 1 of Ignore

Timestamp:

05/02/10 13:41:25 (15 years ago)

Author:

hopscc

Comment:

--

Ignore

@@ +1 @@
+= Ignore = 
+
+Disconnect an event from some particular event handling code by
+specifying an existing event handler (method reference) for a particular 
+Event instance.
+
+This is the converse of [wiki:Listen].
+
+== Grammar ==
+{{{
+ignore <event>, <method-reference>
+}}}
+
+
+== Examples ==
+{{{
+use System.Windows.Forms
+
+...
+        button = Button(parent=p, autoSize=true, text='One', tag=1)
+        # connect event and handling code
+        listen button.click, ref .clickHandler
+        ...
+        # disconnect event and its handling code
+        ignore button.click, ref .clickHandler
+...
+def clickHandler(source as Object, args as EventArgs)  # doClick
+    pass
+}}}
+
+Full example showing signature and event declaration and convenience method for firing/raising an event.
+{{{
+
+# delegate for ActionEvent  <eventName>EventHandler
+sig ActionEventHandler(sender as Object, args as EventArgs)
+
+class Generator
+        # event dcl for event called Action
+        # event <eventName>Event as <sigName> (<eventName>EventHandler)    
+        event actionEvent as ActionEventHandler
+
+        # (protected) method to raise/fire the event for this class 
+        # {on,fire}<eventName>Event
+        def _onActionEvent(args as EventArgs)      # fireActionEvent
+                raise .actionEvent, args
+
+class Listener
+        # the event handler method do<eventName>
+        def doAction(source as Object, args as EventArgs)
+                print 'Event received from [source]'
+
+...
+        def driver
+                g = Generator()
+                l = Listener()
+                
+                #tie the generator event to the Listener method
+                listen g.actionEvent, ref l.doAction
+
+                ...    
+
+                #untie the event and listener
+                listen g.actionEvent, ref l.doAction
+}}}
+
+
+== Notes ==
+
+The event handler method must be a reference to a method not a 
+method invocation.[[BR]]
+
+In practice this means that most ignore statements will have their second
+argument as a method name prefixed with '''ref'''.