Release 10.1A: OpenEdge Getting Started:
Object-oriented Programming

Programming with Class-based and Procedure-based Objects

The CLASS statement provides a clear distinction in Progress between a procedure and a class. Any source file (or larger compilation unit, if you consider the use of include files) that begins with the CLASS statement defines a class, and any file that does not begin with the CLASS statement is a procedure. As you have learned, there are several key differences in the language statements you use in procedures and the statements you use in classes. However, always keep in mind that the vast majority of the Progress language statements are usable in both procedures and classes, and in general have the same behavior, with the exceptions noted as part of this and other chapters of this manual.

Thus, the sections in this chapter describe:

Class-based and procedure-based object compatibility
Handling events
Using widget pools
Referencing routines on the call stack
Comparing handles and object references
Comparing constructs in classes and procedures