All classes deriving from EvtHandler (such as all controls and App) can hold arbitrary data which is here referred to as “client data”. This is useful e.g. for scripting languages which need to handle shadow objects for most of Widgets’ classes and which store a handle to such a shadow class as client data in that class. This data can either be of type void – in which case the data container does not take care of freeing the data again or it is of type ClientData or its derivatives. In that case the container (e.g. a control) will free the memory itself later. Note that you must not assign both void data and data derived from the ClientData class to a container.
Some controls can hold various items and these controls can additionally hold client data for each item. This is the case for Choice, ComboBox and ListBox. TreeCtrl has a specialized class TreeItemData for each item in the tree.
If you want to add client data to your own classes, you may use the mix-in class ClientDataContainer.
EvtHandler, TreeItemData, StringClientData, ClientDataContainer
[This page automatically generated from the Textile source at Wed Sep 09 02:21:02 +0100 2009]