MATLAB Programming

9 Classes and Objects
case '.'
switch index.subs
case 'numShares'
s.numShares = val;
case 'sharePrice'
s.sharePrice = val;
otherwise
s.asset = subsasgn(s.asset,index,val);
end
end
The outer switch statement determines if the index is a numeric or field
name syntax.
The fieldcount asset method determines how many fields there are in the
asset structure and the if statement calls the asset subsasgn method for
indices 1 to fieldcount. See “The Asset fieldcount Method” on page 9-49 and
“The Asset subsasgn Method” on page 9-47 for a description of these methods.
Numeric indices greater than the number returned by fieldcount are
handled by the inner switch statement, which maps the index value to the
appropriate field in the stock structure.
Field name indexing assumes field names other than numShares and
sharePrice are asset fields, which eliminates the need for knowledge of asset
fields by child methods. The asset subsasgn method performs field-name
error checking.
The subsasgn method enables you to assign values to stock object data
structure using two techniques. For example, suppose you have a stock object
s = stock('XYZ',100,25)
You could change the descriptor field with either of the following statements
s(1) = 'ABC';
or
s.descriptor = 'ABC';
9-56