User manual PROGRESS F2

[. . . ] The series compares class syntax with other ABL constructs that may be familiar from earlier product releases, including persistent procedures. [. . . ] It is recommended that you watch the videos in the order they are summarized here. Video Title Introduction to Class Syntax in ABL, Part 1 Video Description In this video we convert a simple ABL persistent procedure, with internal procedures and user-defined functions, to a class that works in a similar way, using the changes as a way to compare language features used in coding procedures with the language syntax for defining classes. Introduction to Class Syntax in ABL, Part 2 This continuation of the introduction illustrates the value of strong typing by showing two "wrapper" procedures that run the procedure and the class built in Part 1, and how the procedure that creates an instance of a class gets more information from the compiler about the correctness of its references to the class. This video shows how to define and use an Interface as a special type of ABL source file that defines prototypes for methods and properties that are then implemented by different classes, which fill in specific behavior for the Using Interfaces as a Programming Contract Generated by Clearspace on 2010-12-27-05:00 1 ABL Videos: Introduction to ABL Classes methods and properties. The Interface definition serves as a contract ­ enforced by the ABL compiler -- that classes implementing the Interface must adhere to, assuring consistency of access to the behavior defined in the Interface. Using Inheritance and Super Classes ­ Part 1 This video is the first of two parts that show the use of inheritance of common behavior using the INHERITS phrase in a class definition. The example also shows how to override a method in a subclass, so that the method's definition is divided between common behavior in the super class and table-specific code in the subclass. This video discusses the importance of encapsulation as a part of object-oriented design, and how it is reflected in the ABL syntax for classes. It also shows an alternative to the method override of the previous videos, which is to overload a Using Inheritance and Super Classes ­ Part 2 Encapsulation and Overloading Generated by Clearspace on 2010-12-27-05:00 2 ABL Videos: Introduction to ABL Classes method by defining multiple versions of the method with the same name but different parameters. Object Life Cycle, and using the CAST Function The final presentation in the series discusses types as definitions of a public interface, classes as implementations of those types, and objects as running instances of classes. [. . . ] It emphasizes what actually gets loaded into memory as an OpenEdge runtime session executes an application, and how garbage collection provides automatic cleanup of objects when they are no longer being used. [. . . ]