Programming

The Asset subsasgn Method

The subsasgn method is the assignment equivalent of the subsref method. This version enables you to change the data contained in an object using one-based numeric indexing and structure field name indexing. The outer switch statement determines if the index is a numeric or field name syntax. The inner switch statements map the index value to the appropriate value in the stock structure.

MATLAB calls subsasgn whenever you execute an assignment statement (e.g., A(i) = val, A{i} = val, or A.fieldname = val).

• function a = subsasgn(a,index,val)
  % SUBSASGN Define index assignment for asset objects
  switch index.type
  case '()'
      switch index.subs{:}
      case 1
          a.descriptor = val;
      case 2
          a.date = val;
      case 3
          a.currentValue = val;
      otherwise
          error('Index out of range')
      end
  case '.'
      switch index.subs
      case 'descriptor'
          a.descriptor = val;
      case 'date'
          a.date = val;
      case 'currentValue'
          a.currentValue = val;
      otherwise
          error('Invalid field name')
      end
  end
  

The subsasgn method enables you to assign values to the asset object data structure using two techniques. For example, suppose you have a child stock object s. (If you want to run this statement, you first need to create a stock constructor method.)

• s = stock('XYZ',100,25);
  

Within stock class methods, you could change the descriptor field with either of the following statements

• s.asset(1) = 'ABC';
  

or

• s.asset.descriptor = 'ABC';
  

See the The Stock subsasgn Method for an example of how the child subsasgn method calls the parent subsasgn method.

The Asset subsref Method

The Asset display Method

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