Tutorial Chapter 3: Displaying Data (Windows/Forms)

Application Overview
This example program opens a window containing a form to display information to the user.

The .4gl File - Opening Windows and Forms
A program creates a window with the OPEN WINDOW instruction, and destroys a window with the CLOSE WINDOW instruction.

The .4gl File - Interacting with the User
Your form can display options to the user using action views - buttons, dropdown menus (topmenus), toolbars, and other items on the window.

The .4gl File - Retrieving and Displaying Data
The example demonstrates how to define a record so you can treat variables as a group. Static SQL instructions retrieve rows from the database which are displayed to the form using the DISPLAY BY NAME statement.

Example: dispcust.4gl (function query_cust)
This function retrieves a row from the customer table and displays it in a form.

The Form Specification File
You can specify the layout of a form in a form specification file, which is compiled separately from your program. The form specification file defines the initial settings for the form, which can be changed programmatically at runtime.

Example: Form Specification File custform.per
This form specification file is used with the dispcust.4gl program to display program variables to the user. This form uses a layout with a simple GRID to define the display area.

Compiling the Program and Form
When this form is compiled (translated) using the Compile menu option in the Project view or the fglform tool, an XML file is generated that has a file extension of .42f. The runtime system uses this file along with your programs to define the Abstract User Interface.