ReAction

Introduction

ReAction is a toolkit for GUI programming in AmigaOS. It is based on Intuition's BOOPSI, an object-oriented philosophy. Understanding the basic concepts of BOOPSI is an important prerequisite for working with ReAction so make sure you have studied the BOOPSI documentation linked above.

Note

There seems to be a certain degree of confusion as regards the relation between ReAction and BOOPSI. It must be understood that the two are not really interchangeable terms (although they are sometimes used in this way). ReAction is a BOOPSI toolkit so there is a part-whole relation between them. ReAction can’t exist without BOOPSI, but BOOPSI can perfectly exist without ReAction. BOOPSI is a general object-oriented programming framework while ReAction is a set of ready-made classes based on this framework.

Originally a third-party product, ReAction became part of the operating system in AmigaOS 3.5. The system, whose internal BOOPSI class set had been rather limited, received a comprehensive toolkit covering most GUI programming needs. Over the years ReAction has grown and matured, with many features added. It is now the recommended toolkit for GUI programming under AmigaOS.

Overview

ReAction is:

object-oriented

All GUI elements created via the toolkit are manipulated as objects of a certain class. The class determines the look, function and general properties of the object; objects of the same class serve the same purpose and share the same properties.

modular and extensible

It is implemented as a set of modules (class libraries) that reside on disk. New classes can be written or derived (“subclassed”) from existing classes, thus adding new functionality to the toolkit.

layout-based

GUI elements provided by the toolkit are meant to be placed in a layout: a structure determining how objects are positioned, sized and grouped in the GUI. Objects governed by a layout are not programmed for specific positions or sizes; instead, these parameters are automatically decided by the layout according to the properties of the individual objects.

BOOPSI-compatible

Program GUIs created through ReAction can include other AmigaOS components based on BOOPSI, such as datatypes or Intuition’s internal BOOPSI classes.

(to be continued)

Context and Input/Output

Describe how input.task is involved, etc.