Added the new common uitask code to the redo.

redo/uitask.go

@@ -0,0 +1,40 @@
+// 6 july 2014
+
+package ui
+
+// TODO Go, Start, Stop
+
+// This is the ui main loop.
+// It is spawned by Go as a goroutine.
+func uitask() {
+	for {
+		select {
+		case req := <-Do:
+			// TODO foreign event
+			issue(req)
+		case <-stall:		// wait for event to finish
+			<-stall		// see below for information
+		}
+	}
+}
+
+// At each event, this is pulsed twice: once when the event begins, and once when the event ends.
+// Do is not processed in between.
+var stall = make(chan struct{})
+
+// This is the common code for running an event.
+// TODO
+// - define event
+// - figure out how to return values from event handlers
+func doevent(e event) {
+	stall <- struct{}{}		// enter event handler
+	c := make(Doer)
+	go func() {
+		e.do(c)
+		close(c)
+	}()
+	for req := range c {
+		issue(req)
+	}
+	stall <- struct{}{}		// leave event handler
+}