Allows the Presentation Server to check and execute all pending events in the Windows Message Queue, returning when the queue is empty. This allows the system to remain responsive during a long running process.
Call Yield( SaveVars )
| Name | Required | Description |
|---|---|---|
| SaveVars | No | If TRUE$ (1) then the following system variables will be saved and then restored after the Yield operation: * @Dict * @Record * @ID * @RecCount * @Rn_Counter The state of Select Cursor 0 will also be saved (via the Push_Select/Pop_Select functions) |
N/A
N/A
Calling the Yield function during a long-running process is important for several reasons:
- It allows screen updates, so that changes to controls can be displayed. - It allows other events to fire so that the user interface remains responsive. - It allows Windows to determine that the process is not "dead" so it will refrain from displaying a "ghost" window with the "Not Responding" caption.
The Yield function is designed to be used from within "Event Context". If called outside of this context it calls the WinYield() function instead.
$Insert Logical
Ctr = 0
Eof = FALSE$
Loop
ReadNext ID Else Eof = TRUE$
Until Eof
Ctr += 1
// Update the progress bar
Call Set_Property_Only( @Window : ".PRB_GASGUAGE", "VALUE", Ctr )
// Allow the progress bar to update and save the
// select state while we do this
Call Yield( TRUE$ )
// Check that the window is still up because the
// user could have closed it during the Yield()
While ( Get_Property( @Window, "HANDLE" ) )
// Do processing etc ...
Repeat
Get_Property, Set_Property, Appendix A - Concatenating Properties.