Programming

The Stock Constructor Method

The stock constructor creates a stock object from three input arguments:

• The stock name
• The number of shares
• The share price

The constructor must create an asset object from within the stock constructor to be able to specify it as a parent to the stock object. The stock constructor must, therefore, call the asset constructor. The class function, which is called to create the stock object, defines the asset object as the parent.

Keep in mind that the asset object is created in the temporary workspace of the stock constructor function and is stored as a field (.asset) in the stock structure. The stock object inherits the asset fields, but the asset object is not returned to the base workspace.

• function s = stock(varargin)
  % STOCK Stock class constructor. 
  % s = stock(descriptor, numShares, sharePrice)
  switch nargin
  case 0 
  % if no input arguments, create a default object
      s.numShares = 0;
      s.sharePrice = 0;
      a = asset('none',0);
      s = class(s, 'stock',a);      
  case 1
  % if single argument of class stock, return it
      if (isa(varargin{1},'stock'))
          s = varargin{1}; 
      else
          error('Input argument is not a stock object')
      end
  case 3
  % create object using specified values
      s.numShares = varargin{2};
      s.sharePrice = varargin{3};
      a = asset(varargin{1},'stock',varargin{2} * varargin{3});
      s = class(s,'stock',a);
  otherwise
      error('Wrong number of input arguments')
  end
  

Constructor Calling Syntax

The stock constructor method can be called in one of three ways:

• No input argument -- If called with no arguments, the constructor returns a default object with empty fields.
• Input argument is a stock object -- If called with a single input argument that is a stock object, the constructor returns the input argument. A single argument that is not a stock object generates an error.
• Three input arguments -- If there are three input arguments, the constructor uses them to define the stock object.

Otherwise, if none of the above three conditions are met, return an error.

For example, this statement creates a stock object to record the ownership of 100 shares of XYZ corporation stocks with a price per share of 25 dollars.

• XYZStock = stock('XYZ',100,25);
  

Designing the Stock Class

The Stock get Method

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