Constructors in Python [Guide]

Python is one of the most popular programming languages in the contemporary world. Every instance in this programming language is created on an object and hence this is an object-oriented programming language. A Special type of function or method that is used to initialize the instances of distinguished entities of the class are called Python Constructors.

There are two types of Python constructors, namely parameterized and non-parameterized constructors.

Non-parameterized Constructor: These constructors of Python do not have any parameters involved at the time of creation. Non-parameterized constructors are also referred to as default constructors. The parameters are by default obtained from the object that is created for a respective class.

Parameterized Constructor: These constructors have predefined parameters included at the time of creation.

Once the object is created within a class, the constructor is defined in the Python code. The Constructor also ensures that there is enough resource to initiate the execution of code within the object enclosed by a class.

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Python Constructor Creation

It is a must to use the _init_ function or method to create a Python constructor. This method should be invoked immediately after the initialization of the class. Any number of parameters can be passed while creating objects of a class as per your needs after defining and invoking the _init_ method. Constructor is mainly used for initializing the class attributes. A constructor is a must for the functioning of every class created in Python. The code below shows an example of using constructors. 

Python Constructor Creation

The output of the above program may look as shown below.

ID: 101

Name: John

ID: 102

Name: David

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Distinction of Parameterized and Non-Parameterized Constructor

The main difference between parameterized and non-parameterized constructors is that the parameterized constructor embraces a predefined value, whereas non-parameterized constructor do not have any assigned values. The usage of parameterized and non-parameterized constructors vary with the context and program requirement. 

Figure 1 Example for a Python Code with Non-Parameterized Construct

Figure 2 Example of Python code with Parameterized Construct

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Working of a Constructor

The first code statement of the Python code when an object is developed for a Python class. This code statement initiates the object and initializes the execution of an object. The working of constructors mainly lies within two key elements. They are:

  1. _Init_() function
  2. Self-reference

Init() function

When the instance of an object for the associated class is created, this function is invoked. Just like any other function declarations, the affirmation of the Init() function is also done with a ‘def’ keyword. Do not forget to use underscores as a prefix and suffix while declaring the init() function. An example of usage of the init() function in Python code is shown below.

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Self Reference

The Self reference indicates the involvement of the object itself. The functions and parameters of the class to which the object belongs are used for the initialization of the object. The first parameter of the declaration of the content should mention ‘self’. This is to indicate that the exponent should work with the particular object’s attributes. The code fragment given below shows the usage of ‘self’ reference as Python Constructors.

Benefits and features of Constructors in Python

  • One of the crucial benefits of constructors is that they can be used to initialize the objects.
  • Only constructors can set or initialize variables of an instance at final status.
  • The use of constructors can omit the initialization of default values.
  • The first code statement to be triggered for execution when an object is developed with a class in Python is the constructor. All other initializations are made by the initialization of the constructor. 
  • Initialization of constructors is possible even when there are no predefined arguments or parameters.

Constructors have a major role to play in all high-level programming languages. Object-oriented programming languages utilize constructors as the primary constituents of their code. An enhanced initialization of variables of an instance can be accomplished with the use of constructors. Hence, it is important for a Python programmer to master the usage of constructors in a program.

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