Update of /project/cells/cvsroot/Celtk In directory clnet:/tmp/cvs-serv27411

Modified Files: ltktest-cells-inside.lisp Log Message:

--- /project/cells/cvsroot/Celtk/ltktest-cells-inside.lisp 2006/03/22 18:50:08 1.2 +++ /project/cells/cvsroot/Celtk/ltktest-cells-inside.lisp 2006/03/22 20:41:37 1.3 @@ -1,18 +1,73 @@ (in-package :celtk-user) +#|

+The comments throughout this source file cover two broad topics: + + How is programming with Celtk different from LTk? + How is programming with Cells different from without Cells? + +Those questions are different because not everything different about Celtk +depends on Cells. + +The pattern will be to have explanatory comments appear after the explained code. + +|# #+test-ltktest (progn (cells-reset 'tk-user-queue-handler) + ; + ; Tk is fussy about the order in which things happen. It likes: + ; - create widgets .x and .y + ; - make .x the -textvariable of .y + ; - set .x to "Hi, Mom" + ; + ; Tk does not like Step 3 going before Step 2. Unfortunately, in a declarative paradigm + ; one does not specify in what order different things should happen, one just specifies + ; the things we want to have happen. That is a big win when it works. But when it did not + ; I created the concept of a so-called "client queue" where client-code could store + ; order-sensitive tasks, and then allowed the client also to specify the handler for + ; that queue. This handler gets called at just the right time in the larger scheme of + ; state propagation one needs for data integrity. Whassat? + ; + ; Data integrity: when the overall data model gets perturbed by a SETF by imperative code + ; (usually processing an event loop) of some datapoint X , we need: + ; + ; - all state computed off X (directly or indirectly through some intermediate state) must be recomputed; + ; - no recomputation can use datapoints not current with the new value of X; + ; - when invoking client observers to process a change in a datapoint, no observer can use + ; any datapoint not current with X; and a corrollary: + ; - should a client observer itself want to SETF a datapoint Y, all the above must + ; happen not just with values current with X, but also current with the value of Y /prior/ + ; to the intended change to Y. + ; + ; To achieve the above, Cells2 and now Cells3 have taken to using FIFO "unfinished business" queues + ; to defer things until The Right Time. Which brings us back to Tk. Inspect the source of + ; tk-user-queue-handler and search the Celtk source for "with-integrity (:client" to see how Celtk + ; manages to talk to Tk in the order Tk likes. But in short, we just add this requirement: + ; + ; - Client code must see only values current with X and not any values current with some + ; subsequent change to Y queued by an observer + ; (tk-test-class 'ltktest-cells-inside))

+; That is all the imperative code there is to Celtk application development, aside from widget commands. Tk handles some +; of the driving imperative logic, and Celtk internals handle the rest. The application works via rules reacting to change, +; computing new state for the application model, which operates on the outside world via observers (on-change callbacks) triggered +; automatically by the Cells engine. See DEFOBSERVER. + (defmodel ltktest-cells-inside (window) - ((elapsed :initarg :elapsed :accessor elapsed :initform (c-in 0))) + () (:default-initargs :kids (c? (the-kids - (ltk-test-menus) + ; + ; Cells GUIs get a lot of mileage out of the family class, which is perfect + ; for graphical hierarchies. + ; + (ltk-test-menus) ;; hiding some code. see below for deets (mk-scroller - :packing (c?pack-self "-side top -fill both -expand 1") - :canvas (c? (make-kid 'ltk-test-canvas))) + :packing (c?pack-self "-side top -fill both -expand 1") + :canvas (c? (make-kid 'ltk-test-canvas))) + (mk-row (:packing (c?pack-self "-side bottom")) (mk-row (:borderwidth 2 :relief 'sunken) (mk-label :text "Rotation:") @@ -67,7 +122,7 @@ :timers (c? (when (^repeat) (list (make-instance 'timer :tag :moire - :delay 1 + :delay 25 :repeat (let ((m self)) (c? (repeat m))) :action (lambda (timer)