MATLAB Programming

Example — Assets and Asset Subclasses
The stock class display method can now call this method to display the data
stored in the parent class. This approach isolates the stock display method
from changes to the asset class. See “The Stock display Method” on page 9-57
for an example of how this method is called.
TheAssetfieldcountMethod
The asset fieldcount method returns the number of fields in the asset object
data structure. fieldcount enables asset child methods to determine the
number of fields in the asset object during execution, rather than requiring
thechildmethodstohaveknowledgeoftheassetclass. Thisallowsyouto
make changes to the number of fields in the asset class data structure without
having to change child-class methods.
function numFields = fieldcount(assetObj)
% Determines the number of fields in an asset object
% Used by asset child class methods
numFields = length(fieldnames(assetObj));
The struct function converts an object to its equivalent data structure,
enabling access to the structure’s contents.
Designing the Stock Class
A stock object is designed to represent one particular asset in a person’s
investment portfolio. This object contains two properties of its own and
inherits three properties from its parent asset object.
Stock properties:
• NumberShares — The number of shares for the particular stock object.
• SharePrice — The value of each share.
Asset properties:
• Descriptor — The identifier of the particular asset (e.g., stock name,
savings account number, etc.).
• Date — The date the object was created (calculated by the date command).
• CurrentValue — The current value of the asset.
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