Class Binding

The Binding Process

When update method is called, it calls controlToSetting to convert the state of the UI component into a setting value (a string). It will then look in the private settings of the game component for a setting with the provided key name. If the setting does not exist or is different from the the setting returned from controlToSetting, then it will copy the new value into the game component's private settings and mark the sheets listed in the list of card faces as being out of date.

update returns true if it updated the component.

When initComponent method is called, it will first fetch the named setting from the game component's private settings and then call settingToControl to modify the state of the control to reflect the setting value.

Writing Binding Classes
The Binding base class will copy the text that a user writes in a text component to a private setting (for update()) and will set the text in the component to the value of the private setting (for initComponent(). For other kinds of components, you need to create an appropriate subclass that knows about the specific kind of control it is binding the game component state to. To create a subclass you only need to override the controlToSetting() and settingToControl() methods to handle the new type of control. For example, the following binding will bind a checkbox to a yes/no setting value in the game component:

function CheckboxBinding( name, uiControl, gameComponent, sheetsToUpdate ) {
    // call superclass constructor
    Binding.call( this, name, uiControl, gameComponent, sheetsToUpdate );
}

CheckboxBinding.subclass( Binding );

CheckboxBinding.prototype.toSetting = function controlToSetting( control ) {
    if( control.selected )
        return 'yes';
    else
        return 'no';
}

CheckboxBinding.prototype.settingToControl = function settingToControl( control, value ) {
    control.selected = value != null && value.equals( 'yes' );
}

If you wish to create more advanced binding behaviours, such as calling methods on the game component instead of changing private settings, override update and initComponent. It is critical that update method returns true if and only if the setting is updated with a different value.