Exploration Through Example

Here’s a test for the Cappuccino app I’m working on. It’s about what happens when, for example, you click on “blood collection for transfusion” in the right table here:

- (void)testPutBackAProcedure
{
  [scenario
   previousAction: function() {
      [self procedure: “Betical“
            hasBeenSelectedFrom: [”alpha“, “Betical“, “order“]];
    }
  during: function() {
      [self putBackProcedure: “Betical“];
    }
  behold: function() {
      [self listenersWillReceiveNotification: ProcedureUpdateNews
            containingObject: []];
      [self tablesWillReloadData];
    }
  andSo: function() {
      [self unchosenProcedureTableWillContain: [”alpha“, “Betical“, “order“]];
      [self chosenProcedureTableWillContain: []];
    }
   ];
}

Here’s the code to pass the test (after inlining one method):

- (void)unchooseProcedure: (id) sender
{
  [self moveProcedureAtIndex: [chosenProcedureTable clickedRow]
                        from: chosenProcedures
                          to: unchosenProcedures];

  [NotificationCenter postNotificationName: ProcedureUpdateNews
                                    object: chosenProcedures];
  [chosenProcedureTable reloadData];
  [unchosenProcedureTable reloadData];
}

Did the test clarify my design thinking? No, not really. Will it be useful for regression? I doubt it. Is it good documentation for the app’s UI behavior? No.

Something seems wrong here.

Cappuccino’s table views aren’t fully finished, so—in version 0.7.1—you can’t just add radio buttons to a table column and have them work. Nevertheless, I wanted something like this:

Since I spent some time figuring out a workaround, I thought I’d save someone some time and write it up.

The workaround used subclasses of CPCheckbox and CPTableColumn. Those were used in the normal way when laying out the window:

  var checkColumn = [[CheckboxTableColumn alloc] initWithIdentifier:@“checks“];
  // …
  var checkButton = [[CritterCheckBox alloc] init];
  [checkButton setTarget: animalController];
  [checkButton setAction: @selector(toggleAnimal:)];
  [checkColumn setDataCell: checkButton]

(nib2cib doesn’t work yet for my application.)

The controller needs to know which checkbox got clicked. I decided to put an index in each checkbox and implement clickedRow on it. (That allowed the action method to ignore whether it was invoked by the checkbox or by selecting a table row, which turns out to be convenient for this application.) The table column’s dataViewForRow: method returns a numbered checkbox. So far, that looks like this:

@implementation CritterCheckBox : CPCheckBox
{
  (CPInteger) index;
}

- (CPInteger) clickedRow
{
  return index;
}

// …
@end

@implementation CheckboxTableColumn : CPTableColumn
{
}

- (id) dataViewForRow: (CPInteger) row
{
  var retval = [[CritterCheckBox alloc] init];
  var target = [[self dataCell] target];
  [retval setTarget: target];
  [retval setAction: [[self dataCell] action]];
  retval.index = row;
  // ..
  return retval;
}

@end

It turns out that CPTableView makes copies of the cells it gets from the CPTableColumn. It uses CPKeyedArchiver/CPKeyedUnarchiver to do that, so those have to be implemented:

@implementation CritterCheckBox : CPCheckBox
//… 

- (void) encodeWithCoder: (CPCoder)aCoder
{
  [super encodeWithCoder:aCoder];
  [aCoder encodeObject: index forKey: @“critter row index“];
}

- (void) initWithCoder: (CPCoder)aCoder
{
  self = [super initWithCoder:aCoder];
  index = [aCoder decodeObjectForKey: @“critter row index“];
  [self setTarget: GlobalCheckboxTarget];   // < <<<<<<<<<<<<<<<<
  return self;
}

@end

The line marked with arrows is a gross hack. CPControls will archive and unarchive actions, but not targets. I decided to fake that by stuffing the target in a global variable and reassigning it on every unarchiving.

When the column is displayed, some of the checkboxes should start off checked. So when a checkbox is created, it asks its target for the appropriate value in the normal tableView:objectValueForTableColumn:row: way:

- (id) dataViewForRow: (CPInteger) row
{
  // …
  checked = [target tableView: nil
                    objectValueForTableColumn: target.checkColumn
                    row: row];
  if (checked) [retval setState: CPOnState];
  return retval;
}

I know a lot of this is stylistically crummy Objective-J. Part of the reason is that I haven’t figured out an Objective-J style yet.

Suggestions about better approaches welcome.

The CheckboxHacks.j source is available on github. So is the whole tree.