Multi-form Applications

IN THIS CHAPTER

• Myths About the Form Filename, Form Module Name , and Form ID
• Passing Data from the Called Form to the Calling Form
• Form Management in an OPEN_FORM Configuration
• Tracking QUERY_ONLY Mode
• Special Tips for Working with Multi-form Applications
• Summary

Multi-form applications are almost a mandatory feature in any software system that handles multiple logical units. A multi-form application also provides a concise integration of the various logical subunits and allows proper break-up of functionality. For example, such an application might display an initial selection screen showing all customers who have placed orders; it would then invoke order-related form(s) for the particular customer highlighted. Other features, such as comparing the orders of two customers, can be achieved by calling a separate form when the order- related information is displayed.

This chapter presents techniques concerning the management of multi-form applications, including techniques for bidirectional sharing of data between forms, interform navigation, commit processing, and exiting sequence in multi-form applications. An important technique for tracking the query-only mode of a called form is explained. The chapter begins by highlighting the theory behind the form filename, form module name, and form ID, along with the method to read and write their values.