====== Yield subroutine ======


 
==== Description ====
 
 
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.
 
 
 
 
==== Syntax ====
 
 
Call Yield( SaveVars )
 
 
 
 
==== Parameters ====
 
 
 
 
 
 
 
^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)|

 

 


 
==== Returns ====
 
 
N/A
 
 
 
 
==== Errors ====
 
 
N/A
 
 
 
 
==== Remarks ====
 
 
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.
 
 
 
 
==== Example ====
 
<code>
 
$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
 
 
 

</code>

 
==== See Also ====
 
 
Get_Property, Set_Property, Appendix A - Concatenating Properties.