Progress
Programming
Handbook
Less Development Effort Required
A powerful 4GL provides a basic set of operations that do a lot of work with little developer intervention. At the same time, the language allows a fine degree of control over the basic operations it provides. This allows the developer to satisfy a variety of design requirements using the same basic set of tools.
To support an application with a single window, a 3GL like C or COBOL must perform many different input/output operations and keep track of a variety of processing conditions for each operation. In a 4GL like Progress, the same basic set of operations can manage a single application window or many windows, depending on the requirements of the application and the type of user interface environment in which it runs.
For example in Progress, one of the simplest, yet most powerful, tools is the FOR statement. This statement provides iterative record reading and display management capabilities so powerful that you can write an entire application with it.
This is one such classic Progress application:
This statement reads each record from a database table named Item in the sports database provided with Progress. It displays all the fields of each record in a default window frame complete with column labels. Every time the frame fills up, it automatically prompts the user to display the next frame:
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From this simple start, there are dozens of ways to modify this application to select and combine data or change its appearance on the display. Compared with this single FOR statement, to develop this application in a 3GL requires several hundred lines of code.
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