Added the Request model of the new, concurrent API.

redo/request.go

@@ -0,0 +1,69 @@
+// 6 july 2014
+
+package ui
+
+// Doer is a channel that takes Requests returned by the various functions and methods of package ui.
+// There are two main Doers: ui.Do, which is for outside event handlers, and the Doer passed into an event handler function.
+// You should not create or use your own Doers; these are meaningless.
+type Doer chan *Request
+
+// Do is the main way to issue requests to package ui.
+// Requests returned by the various functions and methods of package ui should be sent across Do to have them performed.
+// When an event is dispatched to an event handler, that event handler will receive a new Doer which is active for the life of the event handler, and any requests made to Do will block until the event handler returns.
+var Do = make(Doer)
+
+// Request represents a request issued to the package.
+// These are returned by the various functions and methods of package ui and are sent to either Do or to the currently active event handler channel.
+// There are also several convenience functions that perfrom common operations with requests.
+type Request struct {
+	op		func()
+	resp		chan interface{}
+}
+
+// Response returns a channel which is pulsed exactly once, then immeidately closed, with the response from the function that issued the request.
+// If the function does not return a value, this value will be the zero value of struct{}.
+// Otherwise, the type of this value depends on the function that created the Request.
+func (r *Request) Response() <-chan interface{} {
+	return r.resp
+}
+
+// Wait is a convenience function that performs a Request and waits for that request to be processed.
+// If the request returns a value, it is discarded.
+// You should generally use Wait on functions that do not return a value.
+// See the documentation of Bool for an example.
+func Wait(c Doer, r *Request) {
+	c <- r
+	<-r.resp
+}
+
+// Bool is a convenience function that performs a Request that returns a bool, waits for that request to be processed, and returns the result.
+// For example:
+// 	if ui.Bool(ui.Do, checkbox.Checked()) { /* do stuff */ }
+func Bool(c Doer, r *Request) bool {
+	c <- r
+	return (<-r.resp).(bool)
+}
+
+// Int is like Bool, but for int.
+func Int(c Doer, r *Request) int {
+	c <- r
+	return (<-r.resp).(int)
+}
+
+// String is like Bool, but for string.
+func String(c Doer, r *Request) string {
+	c <- r
+	return (<-r.resp).(string)
+}
+
+// IntSlice is like Bool, but for []int.
+func IntSlice(c Doer, r *Request) []int {
+	c <- r
+	return (<-r.resp).([]int)
+}
+
+// StringSlice is like Bool, but for []string.
+func StringSlice(c Doer, r *Request) []string {
+	c <- r
+	return (<-r.resp).([]string)
+}