In a subclass a calling to a constructor of superclass
Call Superclass Constructor ExplicitlyExplicitly calling each superclass constructor from a subclass constructor enables you to: Show
If you do not explicitly call the superclass constructors from the subclass constructor, MATLAB implicitly calls these constructors with no arguments. The superclass constructors must support the no argument syntax to support implicit calls, and the constructors are called in the order they appear at the top of the class block, from left to right. To change the order in which MATLAB calls the constructors or to call constructors with arguments, call the superclass constructors explicitly from the subclass constructor. If you do not define a subclass constructor, you can call the default constructor with superclass arguments. For more information, see Default Constructor and Implicit Call to Inherited Constructor. Call Superclass Constructor from SubclassTo call the constructor for each superclass within the subclass constructor, use the following syntax:
Where For
example, the following segment of a class definition shows that a class called classdef Stocks < Assets methods function s = Stocks(asset_args,...) if nargin == 0 % Assign values to asset_args end % Call asset constructor s@Assets(asset_args); ... end end end Subclass Constructors provides more information on creating subclass constructor methods. Reference Superclasses Contained in PackagesIf a superclass is contained in
a package, include the package name. For example, the classdef Stocks < finance.Assets methods function s = Stocks(asset_args,...) if nargin == 0 ... end % Call asset constructor (asset_args); ... end end end Initialize Objects Using Multiple SuperclassesTo derive a class from multiple superclasses, initialize the subclass object with calls to each superclass constructor: classdef Stocks < finance.Assets & Taxable methods function s = Stocks(asset_args,tax_args,...) if nargin == 0 ... end % Call asset and member class constructors (asset_args) s@Taxable(tax_args) ... end end end Subclass Constructor ImplementationTo ensure that your class constructor supports the zero arguments syntax, assign default values to input argument variables before calling the superclass constructor. You cannot conditionalize a subclass call to the superclass constructor. Locate calls to superclass constructors outside any conditional code blocks. For example, the classdef Stocks < finance.Assets properties NumShares Symbol end methods function s = Stocks(description,numshares,symbol) if nargin == 0 description = ''; numshares = 0; symbol = ''; end (description); s.NumShares = numshares; s.Symbol = symbol; end end end Call Only Direct Superclass from ConstructorCall only direct superclass constructors from a subclass constructor. For example, suppose class The following implementations of
classes Class classdef A properties x y end methods function obj = A(x) ... obj.x = x; end end end Class classdef B < A methods function obj = B(x,y) ... obj@A(x); obj.y = y; end end end Class classdef C < B methods function obj = C(x,y) ... obj@B(x,y); end end end Related Topics
How does a subclass call the superclass constructor?A subclass can call a constructor defined by its superclass by use of the following form of super: super(parameter-list); Here, parameter-list specifies any parameters needed by the constructor in the superclass. super( ) must always be the first statement executed inside a subclass constructor.
Which of this keyword can be used in a subclass to call the constructor of superclass in Java?The super keyword refers to superclass (parent) objects. It is used to call superclass methods, and to access the superclass constructor.
How does a subclass call a superclass method?Subclass methods can call superclass methods if both methods have the same name. From the subclass, reference the method name and superclass name with the @ symbol.
How does a subclass call the superclass constructor quizlet?How does a Subclass call the Superclass constructor? Using the super keyword in the first line of the subclass constructor.
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