Browse Prior Art Database

Filtering the Output of a List

IP.com Disclosure Number: IPCOM000101150D
Original Publication Date: 1990-Jul-01
Included in the Prior Art Database: 2005-Mar-16
Document File: 1 page(s) / 34K

Publishing Venue

IBM

Related People

Black, R: AUTHOR [+4]

Abstract

Described is a technique to allow applications to selectively show parts of a list.

This text was extracted from an ASCII text file.
This is the abbreviated version, containing approximately 98% of the total text.

Filtering the Output of a List

       Described is a technique to allow applications to
selectively show parts of a list.

      How does an application selectively show part of a list?  This
subset must have the look and feel of the full list to the
application and user.  Later the application must be able to quickly
display the whole list or another subset without having to pass all
the data to the list again.

      Applications are provided with a message that will indicate
that list filtering is desired.  This message will have two
parameters, the first is a pointer to a filtering subroutine, the
second is a structure that list will use to pass the list item's data
structure to the supplied subroutine.  The filtering subroutine, that
was supplied to the list by the application, is called to review each
item in the list.  It must decide whether or not an item will be
displayed.  The filtering subroutine returns a TRUE if it is to be
displayed and a FALSE if not.  When an application no longer wishes
to see the filtered list, the same message is sent to list with both
parameters NULL.  The full list of items will once more be displayed.
Internally, the list program keeps two chained sets of pointers (one
for each item), one for the full list and a second for the filtered
one.

      This technique allows an application to easily and quickly show
subsets of a list.  When it wishes, it can have the original list
redisplayed without having to recre...