Progress
Language Tutorial
for Character
Summary
The Progress programming model is a way of programming that creates highly responsive interfaces. A user interface is made up of a keyboard, or other input device such as a mouse, and whatever the user sees on the screen.
A window is an object that contains your application’s workspace. Character interfaces use only one window. Graphical interfaces, such as Windows 95 or Windows NT, can have multiple overlapping windows on the screen.
Progress interfaces are made of objects called widgets. An interface is a tool for displaying data and receiving events. A particular interface can receive events when it is enabled for input and the procedure or the user designates that widget as the event receiver. A widget so designated is said to have input focus.
Each widget responds to each possible user event (keyboard or mouse action) with a default response. You can program a widget to have a response in addition to the default response using triggers. A trigger is a block of code following an ON statement. The code executes when the widget specified in the ON statement receives the user event specified in the ON statement.
The parts of a Progress procedure include:
Progress has the following widgets:
- Window Widgets — Window widgets are workspace for your application. A window contains all other widgets. Character interfaces use one window, while graphical interfaces can use multiple windows.
- Container Widgets — Container widgets allow you to organize data, action, and graphic widgets. Container widgets include frames and dialog boxes.
- Data Widgets — Data widgets are the widgets you use to represent data from fields and variables. Data widgets include fill-in fields, text, editors, selection lists, combo boxes, radio sets, toggle boxes, sliders, and browse widgets.
- Action Widgets — Action widgets allow the user to direct the operation of your application. Menus provide groups of related processing options while buttons execute a single option. Buttons, menu bars, submenus, and menu items make up action widgets.
- Graphic Widgets — Graphic widgets help you decorate your interface. Use rectangles to make different kinds of borders. Images, which are available on graphical interface systems, allow you to include high-resolution graphics in your interface.
You learned about these Progress statements:
- DEFINE VARIABLE creates a variable for use in your procedure.
- DISPLAY displays widgets and the data contained in the associated fields.
- ENABLE turns on widgets for interaction with the user.
- DISABLE turns off widgets.
- WAIT-FOR blocks execution and establishes the condition that unblocks execution.
- ON sets up a widget-event pair that executes a trigger.
- DEFINE BUTTON creates a button.
- DEFINE RECTANGLE creates a rectangle.
- DEFINE FRAME creates a frame, including the field-level widgets that it contains.
- VIEW makes visible frames or widgets within frames.
- HIDE makes invisible frames or widgets within frames.
- ASSIGN explicitly assigns attribute values to widgets.
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