The loadobj Method :: Classes and Objects (Programming)

Programming

The loadobj Method

MATLAB looks for the portfolio loadobj method whenever the load command detects portfolio objects in the .mat file being loaded. If loadobj exists, MATLAB passes the portfolio object to loadobj, which must then return the modified object as an output argument. The output argument is then loaded into the workspace.

If the input object does not match the current definition as specified by the constructor function, then MATLAB converts it to a structure containing the 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 input argument has been converted to 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

The saveobj Method Changing the Portfolio Constructor