python class definition - Wikitechy

What is init function in Python ?

Editor — Sun, 18 Jul 2021 14:00:00 +0000

Python init():

In Python, __init__() method within a class is its constructor.Any method or variable that starts with double underscore is by default private.
Python defines several standard private methods that have a special meaning, and __init__() is one of them. Some others are __str__(), __repr__(), __add__() and others.

What does def init do in Python ?

The __init__ function is known as a constructor, or initializer, and is automatically called when you create a new instance of a class. Within that function, the recently created object is assigned to the parameter “self”. The notation self.legs is an attribute called legs of the object in the variable self.

Sample Code:

class my_class(object):
  def __init(self, x, y):
    self.x = x
    self.y = y
def f2(self):
    return self.x + self.y
 a = my_class(10, 20)
print a.f2()

Output :

In the constructor __init__() and method f2(), a initial parameter self is a reference to a object that will later invoke methods at run time. Actually leaving out self parameter in the definition makes it not possible to call it on behalf of the object.

What is DEF function in Python ?

Editor — Sun, 18 Jul 2021 13:58:09 +0000

DEF function in Python

The Python Def function is the User-Defined one.
Function blocks start with the keyword def then followed by the function name and parentheses ( ( ) ).
Any input parameters must place inside the parentheses. Now you can define parameters inside the parentheses.
The initial statement of a function is optional statement – the documentation string of the function (docstring).
Within the code block each and every function begins with (:) colon and is indented.
The statement return [expression] exits the function, alternatively passing back the expression to caller. The return statement with no arguments is the similar as return none.

Syntax:

def functionname( parameters ):
   "function_docstring"
   function_suite
   return [expression]

What is Classes in Python ?

Editor — Sun, 18 Jul 2021 13:53:08 +0000

Classes in Python

Classes means of a bundling data and functionality together. Creating a new class makes a new object, enabling new instances of that type to be made.
Each class instance can have attributes attached to it for maintaining its state. Class instances can also have methods (defined by its class) for modifying its state.
Compared with other programming languages, Python’s class mechanism includes classes with a minimum of new syntax and semantics. It is a blend of the class mechanisms that are found in C++ and Modula-3.
In Python, the class inheritance mechanism allows multiple base classes, a derived class will override some methods of its base class, and the method will call a method of a base class with the same name.
Objects can contain random amounts and kinds of data. It is true for modules, classes split of the dynamic nature of Python: they are created at runtime, and then can be changed further after making.

Syntax:

class ClassName:
   'Optional class documentation string'
   class_suite

The class has a documentation string, which can be accessed via ClassName.__doc__.

The class_suite consists of all the component statement defining class members, data attributes and functions.