MATLAB Programming

9 Classes and Objects
Example — The Portfolio Container
This example is divided into the following topics:
• “Designing the Portfolio Class” on page 9-58
• “The Portfolio Constructor Method” on page 9-59
• “The Portfolio display Method” on page 9-60
• “The Portfolio pie3 Method” on page 9-61
• “Creating a Portfolio” on page 9-62
Aggregation is the containment of one class by another class. The basic
relationship is: each contained class “is a part of” the container class.
For example, consider a financial portfolio class as a container for a set of
assets (stocks, bonds, savings, etc.). Once the individual assets are grouped,
they can be analyzed, and useful information can be returned. The contained
objects are not accessible directly, but only via the portfolio class methods.
See “Example — Assets and Asset Subclasses” on page 9-41 for information
about the assets collected by this portfolio class.
Designing the Portfolio Class
The portfolio class is designed to contain the various assets owned by a given
individual and provide information about the status of his or her investment
portfolio. This example implements a somewhat over-simplified portfolio
class that
• Contains an individual’s assets
• Displays information about the portfolio contents
• Displays a 3-D pie chart showing the relative mix of asset types in the
portfolio
Required Portfolio Methods
The portfolio class implements only three methods:
9-58