FILTER.ACTIVE [Revelation On-Line Wiki]

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====== FILTER.ACTIVE=====

^Published By^Date^Version^Knowledge Level^Keywords^
|Revelation Technologies|14 NOV 1989|2.X|EXPERT|FILTER.ACTIVE|

==== FILTER.ACTIVE ====

FILTER.ACTIVE is a subroutine that activates and executes 
the specified filter.

<code>
FILTER.ACTIVE(filter.key, filter)
</code>

==== Using FILTER.ACTIVE ====

Use FILTER.ACTIVE to activate a selection process that can 
optionally have been stored as a record in a file (FILTERS, 
for example).  This subroutine also updates the system 
variable @LAST.SELECT.PROCESS  with the value of filter.key, if 
any.

=== filter.key ===

Use filter.key to pass the record key of the specified 
filter.  This is used to reset @LAST.SELECT.PROCESS (see 
Appendix 1, "System Variables").

=== filter ===

Use filter to pass the filter to be used.  Filter is a regular 
SELECT statement except that the word SELECT must not be 
used.  FILTER.ACTIVE will supply the word "SELECT".
If a browse list is currently active (@BROWSE.MODE is true), 
it is saved and restored upon execution of filter.

==== Values returned ====

None.  The filter is activated.  If @BROWSE.MODE is true 
(see Appendix 1, ``System Variables''), the select list is 
converted to a browse list (truncated to 32K).  
@LAST.SELECT.PROCESS is reset to filter.key.

==== Correct Use of FILTER.ACTIVE ====

<code>
/* The following code specifies a filter, then activates and 
executes it by means of FILTER.ACTIVE.  It also updates 
@LAST.SELECT.PROCESS with the name of the filter.  Both the 
name of the filter and the filter specification could have 
come from a file, as for example, from FILTERS, where the 
name would be the record key. */

DECLARE SUBROUTINE FILTER.ACTIVE

filter.key = "TEST.FILTER"
filter     = "SAMPLE_CUSTOMERS WITH STATE = 'NY'"

FILTER.ACTIVE(filter.key, filter)
PERFORM "LIST SAMPLE_CUSTOMERS"
</code>