As an alternative to creating a derived class to manage complex dialog boxes or windows with many child-window controls, you can use a structure to represent the state of the dialog box's or the window's controls.

This structure is called a transfer buffer because control states are transferred to the buffer from the controls and to the controls from the buffer.

For example, your application can bring up a modal dialog box and, after the user closes it, extract information from the transfer buffer about the state of each control. Then, if the user brings up the dialog box again, you can transfer the control states from the transfer buffer. In addition, you can set the initial state of each control based on the transfer buffer. You can also explicitly transfer data in either direction at any time, such as to reset the states of the controls to their previous values. A window or modeless dialog box with controls can also use the transfer mechanism to set or retrieve state information at any time.

The transfer mechanism requires the use of ObjectWindows objects to represent the controls for which you'd like to transfer data. To use the transfer mechanism, you have to do three things:

Define the transfer buffer, with an instance variable for each control for which you want to transfer data.
Define the corresponding window or dialog box.
Transfer the data.

See Also