Re: behaviour of save qualifier to on-break

[Ray Ontko <rayo@ONTKO.COM>]

Mainoo,

> i am confused by the workings of 'on-break' and its 'save' qualifier.
> is it the case that the variable supplied to save is initialised with
> the first occurrence of the break field even BEFORE an on-break occurs?
>
> from what i can see the first occurrence of a field that has on-break set
> does not trigger the on-break command yet the save variable is set
> during the processing of the first occurrence. the on-break command is
> triggered for the first time on transition from the first to the second
> occurrence.

Here's my understanding of how it works.  When the begin-select
starts, all save= variables are cleared.  Then the before=
procedure is executed, then the new values are saved into the save=
variables, then when the value changes the new value appears in
the "&" variable and the after= procedure is fired, then the
before procedure is fired, etc.

A simple test program demonstrates the behavior.  My two tables
are named T and U, and the output and program listing are shown
below.

Ray
-----

pre junk,
before ,T
during T,T
after T,U
before U,U
during U,U
after U,U
post U,U

-----

begin-program
do main
end-program

begin-procedure main
move 'junk' to $old_table_name
show 'pre ' $old_table_name ','  &table_name
begin-select
table_name &table_name () on-break print=never save=$old_table_name
   before=b after=a
   show 'during ' $old_table_name ','  &table_name
from user_tables
end-select
show 'post ' $old_table_name ','  &table_name
end-procedure ! main

begin-procedure a
show 'after ' $old_table_name ','  &table_name
end-procedure

begin-procedure b
show 'before ' $old_table_name ','  &table_name
end-procedure

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Ray Ontko       |  Ray Ontko & Co  |  "Time for a new signature line."
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