Date: Mon, 30 Oct 2000 09:25:55 -0500 From: Gail Kahn Subject: November PUF Meeting Announcement Paradox User's Forum Date and Time: Monday, November 6, 6:45 PM Meeting Topic: "Transitive Data Validation Dependency" by Al Breveleri Description: GUI controls, or field objects, usually restrict the operator's input, for example, with a list, dropdown list, edit mask, etc. One of the most powerful techniques available to an interface developer is to dynamically alter the restrictions of one field in response to the data entered in another. However, when more than three or four fields affect one another in this way, and with the operator free to focus on the fields in any order, the coding involved can become ... involved. The theory of Transitive Data Dependency attempts to abstract the common features and characteristics of fields which rely dynamically on the contents other fields for presentation and validation. The theory describes how to extend the event model of a GUI control, to allow a designer to insure that restrictions get updated at the proper times by simply linking fields together and filling out the methods that construct the restrictions. The presentation will include a description of the theory as it now stands, several prototype implementations in Paradox for Windows, and many opportunities for questions, proposals, and suggestions. Meeting Location: New Horizons Computer Learning Center, 5 Old Concord Road, Burlington, MA. [Directions: Take Exit 32B on Route 128. Turn Left onto Middlesex Turnpike (proceeding south, away from the Burlington Mall, staying inside Route 128). Turn left at the first light onto Wheeler Road, and left again onto Old Concord Road. Parking is free.] For Information: Call David Kahn at 508-651-3112, FAX: 508-651-3233, http://www.dlawton.com/bcdug.htm or email: bcdug@dlawton.com.