Getting Started
In VisualAge, a part is a self-contained software object with a
well-defined public interface that establishes the features of the
part.
There are three types of parts that you work with in VisualAge:
- Visual part
- A part that has a visual appearance at run time. Visual parts, such
as windows, push buttons, and entry fields, make up the user interface of an
application. Visual parts can contain other visual parts, nonvisual
parts, connections to other parts and IBM Smalltalk code. The
Composition Editor is the primary tool used to create and modify visual
parts.
- Nonvisual part
- A part that has no visual appearance at run time. A nonvisual part
typically represents behaviors or data within an application. Nonvisual
parts can contain other nonvisual parts, connections to other parts and IBM
Smalltalk code. The Composition Editor is the primary tool used to
create and modify nonvisual parts.
- Smalltalk class
- A Smalltalk class and associated methods may be used to implement behavior
or represent data directly through the use of the IBM Smalltalk
language. The Script Editor is the primary tool used to create and
modify Smalltalk classes.
A part's public interface determines how it can interact with other
parts. The public interface of a part consists of the following types
of features:
- Attributes
- Data that can be accessed by other parts. This data can represent
any logical property of a part, such as the balance of an account, the size of
a shipment, or the label of a push button.
- Events
- Signals that indicate something has happened, such as opening a window or
changing an attribute's value.
- Actions
- Operations or functions that a part can perform. Actions can be
triggered by connections from other parts.
Parts placed inside of other parts are called subparts. A
part that contains other parts is called a composite part.
All parts can be reused as subparts of composite parts.
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