HP 3000 Manuals

HP ALLBASE/4GL Developer Self-Paced Training Guide

Display Field Processing 

HP ALLBASE/4GL performs display field processing for every field (display
and input) on the screen.  The display processing for a field occurs when
control first passes to the field.


            

   1.  HP ALLBASE/4GL determines if a primary data movement field is
       specified for this screen field.  If one is specified, processing
       branches to step 4.

   2.  This step checks if a default data movement field is specified.
       If not, processing branches to step 6.

   3.  The current screen field's buffer is tested.  If it contains data,
       processing branches to step 6.  HP ALLBASE/4GL only moves data
       from the default data movement field to the screen field buffer if
       the screen field buffer is blank.

   4.  HP ALLBASE/4GL moves data from the primary data movement field (or
       the default data movement field) to the screen field buffer.

   5.  The screen field buffer contents are justified as required and
       filled, if necessary, with the pad character.  They are not
       immediately displayed on the screen.

   6.  The switch *ENTERED is set off.

   7.  If there is a prior function assigned to the field, (that is, the
       function has been defined to be executed either prior to or, both
       prior and after data entry), then it is executed now.  This
       function can test *ENTERED to determine when it is being called.

   8.  Finally, the contents of the screen buffer are displayed in the
       screen field.

       Display field processing is now complete and control returns to
       the full data screen processing logic described earlier.

MPE/iX 5.0 Documentation