Python Class & object

Classes are binding of data and function into single unit. When we create a class in our source code that means we are create a new type of object. this object is used to access class properties like such as method and data.

Classes are provide most useful feature of object oriented programming (Oop) like inheritance, encapsulation, operator overload and so on. define class of python by using of following syntax.

class class_name:
  #statement1
  #statement2
  #statement N

There is possible to define python class in various place. Here given of few examples.

Define a class

#case 1: define a class 
class Programming:
   def info(self):
     print("Python")
obj=Programming() #create object
obj.info() #access function of class
Output
Python
Define A Python Class

In this example Programming is an class. and we are create a instance obj (object) of this class. and info is an function (class attributes). this attribute are access by the class object. in this case obj.info() is execute class function. and self is an reference to calling object.

Define class in inside function

# Case 2: define class in  inside function
def operation():
  class Inner(object):
    """Function of Inner class"""
    def info(self):
      print("information")
  obj=Inner()
  obj.info()    
operation() #call function
Output
information
Python Class Inside Function

In of given example define of python class are within the function. scope of this class is start when execute this function. And scopes is over when executed all statement of this function. so this class scope is dependent of function scopes.

Define class within if statements

#Case 3: define within if statements
test=1
if(test==1):
  class PythonTest:
    def info(self):
      print("PythonTest info function")
  class CppTest:
    def info(self):
      print("CppTest info function")
  
  #PythonTest class object    
  python=PythonTest()
  
  #CppTest class object   
  cpp=CppTest()
  
  python.info()
  cpp.info()
else :
  print("Test is Fail Try again") 
Output
PythonTest info function
CppTest info function
python class within if statement

In this example defined class within if statement. So when this statement expression are valid then scopes are start inside class. and observe that both class are same method ("info"). this methode are used by class object.

Basic knowledge of python class

Class attributes: There is two types data attributes and method attributes. data attributes is related to class variables, and method attributes are related to function. For example.

#class attributes example
class Records:
    #setRecord is method attributes 
  def setRecord(self,data): 
    #info is data attributes
    self.info=data 
  def getRecord(self):
    return self.info

record=Records(); #create class object
#access method attributes
record.setRecord("Python v3") 
#print data attributes value
print(record.getRecord()) #display value 
Output
Python v3

class instance (objects) : class are combine the method and data. and creating a namespace and scopes. help of class object can be access this namespace attributes. there is defined by using of following syntax.

object_name=ClassName()

Let take an example.

#class object example
#Create a class Test
class Test:
    #setRecord is method attributes 
  def setRecord(self,data): 
    #info is data attributes
    self.info=data 
  def getRecord(self):
    return self.info

record1=Test(); #create first object
record2=Test(); #create second object

#set object data attribute value
record1.setRecord("Python Test") 

#set object data attribute value
record2.setRecord("Java Test") 

#Dispay data attribute of record1
print(record1.getRecord()) 

#Dispay data attribute of record2
print(record2.getRecord()) 
Output
Python Test
Java Test
Class Instance

In this example there are two object of class Records. that are binding separate data attributes. that are shared common method but there data attributes are different. And there are no limits to create any number of class instance (objects).

__init__() methods: This is an special methods of class that are automatic invoked when create an class object. this will used to provide an initial value to data attributes. that are similar to constructor of c++ programming. for example

#class __init__ method example
class Test:
  #special method
  def __init__(self,data1,data2): 
    #set initial value
    self.info1=data1 
    self.info2=data2
  def display(self):
    print(self.info1)
    print(self.info2)

record1=Test(1,2); #create class object
record2=Test(7,9); #create class object
record1.display();
record2.display();
Output
1
2
7
9
Class Int method


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