MATLAB Programming

Example — Defining saveobj and loadobj for Portfolio
same fields and the object’s structure with all the values intact (that is, you
now have a structure, not an object).
The following implementation of loadobj first uses isa to determine whether
the input argument is a portfolio object or a structure. If the input is an
object, it is simply returned since no modifications are necessary. If the
inputargumenthasbeenconvertedto a structure by MATLAB, then the
new accountNumber field is added to the structure and is used to create an
updated portfolio object.
function b = loadobj(a)
% loadobj for portfolio class
if isa(a,'portfolio')
b = a;
else % a is an old version
a.accountNumber = getAccountNumber(a);
b = class(a,'portfolio');
end
Changing the Portfolio Constructor
The portfolio structure array needs an additional field to accommodate the
account number. To create this field, add the line
p.accountNumber = '';
to @portfolio/portfolio.m in both the zero argument and variable
argument sections.
The getAccountNumber Function
In this example, getAccountNumber is a MATLAB function that returns
an account number composed of the first three letters of the client name
prepended to a series of digits. To illustrate implementation techniques,
getAccountNumber is not a portfolio method so it cannot access the portfolio
object data directly. Therefore, it is necessary to define a portfolio subsref
method that enables access to the name field in a portfolio object’s structure.
For this example, getAccountNumber simply generates a random number,
which is formatted and concatenated with elements 1 to 3 from the portfolio
name field.
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