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If the class being created is a subclass, MATLAB calls the constructor of each superclass class to initialize the object. Initializing object state, such as property values, for each instance of the classĬalling the superclass constructor with values that are determined by the subclass constructorįor information specific to constructing enumerations, see Enumeration Class Constructor Calling Sequence.įor information on creating object arrays in the constructor, see Construct Object Arrays. For example, when creating an object of the class requires: When to Define Constructorsĭefine a constructor method to perform object initialization that a default constructor cannot perform. This behavior is useful when there is no need for a subclass to define a constructor, but the superclass constructor does require input arguments. When a subclass does not define a constructor, the default constructor passes its inputs to the direct superclass constructor. The default constructor supplied by MATLAB also calls all superclass constructors with no arguments or with any argument passed to the default subclass constructor. If a class does not define a constructor, MATLAB supplies a default constructor that takes no arguments and returns a scalar object whose properties are initialized to property default values. See No Conditional Calls to Superclass Constructors for more information.

You cannot place superclass construction calls in loops, conditions, switches, try/catch, or nested functions. If your constructor makes an explicit call to a superclass constructor, this call must occur before any other reference to the constructed object and cannot occur after a return statement.Ĭalls to superclass constructors cannot be conditional. See No Input Argument Constructor Requirement. If you create a class constructor, ensure it can be called with no input arguments. If you do not want to assign the output argument, you can clear the object variable in the constructor (see Output Object Suppressed). The constructor can return multiple arguments, but the first output must be the object created. The constructor has the same name as the class.