Class ListView

Inheritance:

Object  »
  View  »
    ListView
      PluggableListView  »
        PluggableListViewByItem  »
        PluggableListViewOfMany  »

Preferred controller: ListController.

This view displays a scrollable list of selectable items. The user can select one item; to do that, he clicks on the item with the red (left) mouse button.

The ListView is hardly ever used, sometimes it is even said that ListView is an abstract class. The PluggableListView is normally used because of its great flexibility.

ListView is not an abstract class, it is best used with a model that follows the value holder pattern.

To support the ListView, a model has to implement these methods:

• list
  The method has to return a sequenceable collection of strings. The strings should not contain line breaks.

• listIndex
  The method has to return an integer, the index of the currently selected item. The value of 0 indicates that no item is currently selected.

• toggleListIndex: anInteger
  This method is sent from a ListController to inform the model about a selection.

Instance Variables:

• list - ListParagraph
  The ListParagraph is a displayable representation of the list items.

• selection - Integer
  The index of the currently selected item. A value of 0 indicates that no item is currently selected.

• topDelimiter - String
  The string that is used to mark the top of the item list.

• bottomDelimiter - String
  The string that is used to mark the bottom of the item list.

Update Behavior:

ListView is not a pluggable view. Update methods do not compare a message argument with stored selectors, but simply react to some fixed symbols.

• update
  no action is triggered by this message
• update: aSymbol
  
  • aSymbol == #list
    The list is refreshed from the model, the current selection is dropped. The new list is displayed.
  • aSymbol == #listIndex
    The model is asked for the current selection. The current selection is displayed. If necessary, the list is scrolled to make the current selection visible.

Class ListView is now infrequently used because it is a bit inflexible. An instance of this class is best used with a model of its own. A suitable model class is currently not available, it should be a subclass of ValueHolder.

Example of Use:

You find an example on page List View Example.