Class Constructor Methods in MATLAB

In MATLAB, there are class constructor methods which are used to create an instance of a class. Class constructor methods are basically special functions within a class that are used to create and initialize the objects of the class, these class constructor methods are called automatically when we create a new object in the class. In this tutorial, I will explain class constructor methods in MATLAB in detail.

What is the Purpose of Class Constructor Methods?

As mentioned above, a class constructor method in MATLAB is a special function which is used to create an instance of a class. In simple terms, the purpose of class constructor methods in MATLAB is to create and initialize an object from a class.

The key purposes of the class constructor methods are as follows:

• Class constructor methods ensure the proper initialization of objects when they are created. It helps to avoid invalid state of the objects by setting proper initial values of all necessary properties.

• Class constructor methods help to encapsulate the implementation details of objects from the users. Hence, it provides better code organization and minimizes the risk of accidental changes in the properties of the objects.

• Class constructor methods make object creation and initialization flexible. They provide several different ways to create objects.

• Class constructor methods provide a consistent way of creating objects from the class.

Overall, class constructor methods in MATLAB are very important, as they ensure appropriate creation and initialization of objects.

Guidelines for Class Constructors

In MATLAB, the important guidelines for creating class constructor methods are listed here:

• The class constructor must have the same name as the class.

• The class constructor can return multiple output arguments. However, the first output argument must always be the object created.

• If you do not have to assign the output argument in the constructor, in that case you can clear the object variable within the constructor. It helps you when you want to create an object but do not intend to use it immediately.

• When you create a class constructor, you should always ensure that it can be called without any input arguments. It makes creation of objects versatile.

• If your class inherits from a superclass and your constructor makes a call explicitly to a superclass constructor. Then, this call to the superclass constructor must occur before any other reference to the constructed object within the constructor, and it can never occur after a return statement.

• You have to avoid the conditional calls to superclass constructors. That is, you cannot place calls to superclass constructors in loops, conditions, switches, try/catch blocks, or nested functions. Therefore, the superclass constructors must be unconditional and straightforward.

After getting a brief overview of class constructor methods in MATLAB, let us now understand the concept class constructor method with the help of an example.

Defining Class Constructor Methods

The following syntax is used to define a class constructor method in MATLAB.

classdef SampleClass
   properties
      Property1
      Property2
      Property3
   end

   methods
      function obj = SampleClass(argument1, argument2, argument3)
         % Your constructor code?
      end
   end
end

Now, let us consider an example to understand the concept practically.

Example

Consider we intend to create a class namely, 'Tutorials' that has two properties i.e., 'name' and 'fee'. This class can be defined as follows:

classdef Tutorials
   properties
      name
      fee
   end

   methods
      function obj = Tutorials(name, fee)
         obj.name = name;
         obj.fee = fee;
      end
   end
end

In this code, there is a class with name 'Tutorials' which has two properties namely, 'name' and 'fee'. Also, this class has a method with name 'Tutorials' which is basically the class constructor. In this example, this class constructor is taking two arguments i.e., 'name' and 'fee'.

Now, if we want to create an instance of this class 'Tutorials', we can use the 'Tutorials' constructor as follows:

c1 = Tutorials('MATLAB', 3000);

This code will create an object with name 'c1' of the 'Tutorials' class, where the properties will be name = MATLAB and fee = 3000.

To access the properties of this object, we can use the following code:

% To access output name
c1.name

% To access output fee
c1.fee

Output

The output will be,

'MATLAB'
3000

Now, let us see how we can change the properties of the object. For this, we can use the dot notation as follows:

% To change name property
c1.name = 'Python';

% To change fee property
c1.fee = 4000;

Output

If we now access the properties, the output will be,

'Python'
4000

Conclusion

In conclusion, class constructor methods are important concepts in MATLAB programming that allow use to create and initialize objects when they are created. This concept serves various important purposes such as object initialization, encapsulation, consistency, flexibility, etc.

Using class constructors, we can create a well-organized and easy to maintain object-oriented code in MATLAB programming.