6.5.3 Changes to method definitions

The definitions for the methods given in Chapter 5 must be redefined so as to take an instance of <frame> as an argument, rather than an instance of <gadget>. This change results in these new definitions:

define method open-file
    (frame :: <task-frame>) => ()
  let task-list = frame-task-list(frame);
  let filename
    = choose-file(frame: frame,
                  default: task-list.task-list-filename,
                  direction: #"input");
  if (filename)
    let task-list = load-task-list(filename);
    if (task-list)
      frame.frame-task-list := task-list;
      refresh-task-frame(frame)
    else
      notify-user(format-to-string("Failed to open file %s", filename),
                  owner: frame)
    end
  end
end method open-file;

define method save-file
    (frame :: <task-frame>) => ()
  let task-list = frame-task-list(frame);
  if (task-list.task-list-modified?)
    save-as-file(frame, filename: task-list.task-list-filename)
  end
end method save-file;

define method save-as-file
    (frame :: <task-frame>, #key filename) => ()
  let task-list = frame-task-list(frame);
  let filename
    = filename
        | choose-file(frame: frame,
                      default: task-list.task-list-filename,
                      direction: #"output");
  if (filename)
    if (save-task-list(task-list, filename: filename))
      frame.frame-task-list := task-list;
      refresh-task-frame(frame)
    else
      notify-user(format-to-string
                    ("Failed to save file %s", filename),
                  owner: frame)
    end
  end
end method save-as-file;

define method frame-add-task (frame :: <task-frame>) => ()
  let task-list = frame-task-list(frame);
  let (name, priority) = prompt-for-task(owner: frame);
  if (name & priority)
    let new-task = make(<task>, name: name, priority: priority);
    add-task(task-list, new-task);
    refresh-task-frame(frame);
    frame-selected-task(frame) := new-task
  end
end method frame-add-task;

define method frame-remove-task (frame :: <task-frame>) => ()
  let task = frame-selected-task(frame);
  let task-list = frame-task-list(frame);
  if (notify-user(format-to-string
                    ("Really remove task %s", task.task-name),
                  owner: frame, style: #"question"))
    frame-selected-task(frame) := #f;
    remove-task(task-list, task);
    refresh-task-frame(frame)
  end
end method frame-remove-task;

define method note-task-selection-change
    (frame :: <task-frame>) => ()
  let task = frame-selected-task(frame);
  if (task)
    frame.priority-box.gadget-value := task.task-priority;
  end;
  command-enabled?(frame-remove-task, frame) := task ~= #f;
end method note-task-selection-change;

For details about note-task-selection-change, see Section 5.3.3.3 on page 67. See Section A.2, "A task list manager using command tables" for the complete source code for the Task List 2 project.

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Building Applications Using DUIM - 26 May 1999