MATLAB Programming

Example — Defining saveobj and loadobj for Portfolio
Example — Defining saveobj and loadobj for Portfolio
This example is divided into the following topics:
• “Summary of Code Changes” on page 9-65
• “The saveobj Method” on page 9-66
• “The loadobj Method” on page 9-66
• “Changing the Portfolio Constructor” on page 9-67
• “The Portfolio subsref Method” on page 9-68
In the section “Example — The Portfolio Container” on page 9-58, portfolio
objects are used to collect information about a client’s investment portfolio.
Now suppose you decide to add an account number to each portfolio object
that is saved. You can define a portfolio saveobj method to carry out this task
automatically during the save operation.
Suppose further that you have already saved a number of portfolio objects
without the account number. You want to update these objects during the
load operation so that they are still valid portfolio objects. You can do this by
defining a loadobj method for the portfolio class.
Summary of Code Changes
To implement the account number scenario, you need to add or change the
following functions:
• portfolio — The portfolio constructor method needs to be modified to
create a new field, accountNumber, which is initialized to the empty string
when an object is created.
• saveobj — A new portfolio method designed to add an account number
to a portfolio object during the save operation, only if the object does not
already have one.
• loadobj — A new portfolio method designed to update older versions of
portfolio objects that were saved before the account number structure field
was added.
9-65