how does code works

[igor denisov]

There are places marked with question marks where I do not understand
what is going on. Can you explain them?

(in-package :common-lisp-user)
(defpackage :first-app
	    (:use :clim :clim-lisp)
	    (:export first-app))
(in-package :first-app)

(defun av-test-display-screen (frame pane)
  (declare (ignore frame))
  (with-text-size (pane :large)
    (fresh-line pane)
    (present '(com-reset-clock-1) 'command :stream pane)
    (fresh-line pane)))

(define-application-frame av-test ()
  ((own-window-p :initform nil)) ;;  These slots will typically hold
                                 ;;  any per-instance frame state.

  (:menu-bar t)
  (:panes
   (screen :application
           :display-time t
	   :display-function #'av-test-display-screen
           :text-style (make-text-style :sans-serif :roman :normal))
   (interactor :interactor :min-width 600)
   (doc :pointer-documentation))
  (:layouts
   (defaults
	 (vertically ()
	   screen
	   interactor
	   doc))))

;; default-frame-top-level will also establish a simple restart
;; for abort, and bind the standard stream variables. *query-io* will be bound
;; to the value returned by frame-query-io
(defun reset-clock-1 (&key (stream *query-io*) (ow t))
;;                            ^^^    ^^^        ^  ^
;;                     keyword-name   var     k-n  v
  (multiple-value-bind (second minute hour day month)
      (decode-universal-time (get-universal-time))
    (declare (ignore second)) ;; self explanatory, var second is not used
                              ;; anywhere
    (restart-case
	;; restartable-form
	(progn
	  ;; For instance, an accepting-values whose fields consist of
	  ;; gadgets may appear in an ordinary CLIM
          ;; stream pane.
	  ;; For example, accepting-values dialogs can be implemented by
          ;; using an encapsulating stream that tailors calls to accept and
	  ;; prompt-for-accept in such a way that the output is captured and
	  ;; formatted into a dialog that contains prompts and fields
          ;; that can be clicked on and modified by the user.

	  ;; (For example, the behavior of accepting-values can be implemented
	  ;; by creating a special class of stream that turns calls to
	  ;; accept into fields of a dialog.) ????????????? HOW TO???

	  ;; accepting-values (&optional stream &key own-window exit-boxes
	  ;; initially-select-query-identifier modify-initial-query
	  ;; resynchronize-every-pass resize-frame align-prompts label
	  ;; scroll-bars x-position y-position width height command-table
	  ;; frame-class) &body body   [Macro]

	  (clim:accepting-values (stream :own-window ow)
				 ;; (accepting-values (stream :own-window ow)
				 ;;            same as?????
				 ;; (accepting-values
				 ;; (&optional stream
				 ;; &key own-window
				 ;; what is ow)   ??????????
	    (format stream "Enter the time~%")
	    (setq month (clim:accept 'integer :stream stream
				      :default month :prompt "Month"))
	    (terpri stream)
	    (setq day (clim:accept 'integer :stream stream
				    :default day :prompt "Day"))
	    (terpri stream)
	    (setq hour (clim:accept 'integer :stream stream
				     :default hour :prompt "Hour"))
	    (terpri stream)
	    (setq minute (clim:accept 'integer :stream stream
				       :default minute :prompt "Minute")))
	  ;; This could be code to reset the time, but instead
	  ;; we’re just printing it out
	  (format nil "New values: Month: ~D, Day: ~D, Time: ~D:~2,'0D."
		  month day hour minute))
      ;; case-name is abort, it names this restart.
      (abort () (format nil "Time not set")))))

(define-av-test-command (com-reset-clock-1 :name t :menu nil) ()
  (with-slots (own-window-p) clim:*application-frame*
    (format t "Result: ~S~%" (multiple-value-list
			      ;; (defun reset-clock-1
			      ;; (&key (stream *query-io*) (ow t)) ...)
			      (reset-clock-1 :ow own-window-p))))
  (finish-output *standard-output*)) ;;       ^         ^
;;                                                               |
  av-test slot
;;                                                       no idea???
(defun first-app ()
(run-frame-top-level (make-application-frame 'av-test)))

Regards,
Igor.