Built-In Class Attributes in Python

In this article, we will explain to you the built-in class attributes in python

The built-in class attributes provide us with information about the class.

Using the dot (.) operator, we may access the built-in class attributes.

The built-in class attributes in python are listed below −

Now we will see about each one of them in brief along with an example for better understanding

Example 1: __dict__ Class Attribute

Here we are printing the dict of the class.

# creating a class say Tutorialspoint
class Tutorialspoint:
   'Welcome to Tutorialspoint Python'

   def __init__(self):
      print("The __init__ method")

# Printing the value of Built-in __dict__ attribute for the TutorialsPoint class
print(Tutorialspoint.__dict__)

Output

On executing, the above program will generate the following output −

{'__module__': '__main__', '__doc__': 'Welcome to Tutorialspoint Python', '__init__': <function Tutorialspoint.__init__ at 0x7fd7812df050>, '__dict__': <attribute '__dict__' of 'Tutorialspoint' objects>, '__weakref__': <attribute '__weakref__' of 'Tutorialspoint' objects>}

Example 2: __doc__ Class Attribute

In the Python code below, we create a Tutorialspoint class with documentation.

# creating a class say Tutorialspoint
class Tutorialspoint:
   'Welcome to Tutorialspoint Python'

   def __init__(self):
      print("The __init__ method")

# getting the documentation for the Tutorialspoint using
# built-in __doc__ class attribute
print(Tutorialspoint.__doc__)

Output

Welcome to Tutorialspoint Python

Example 3: __name__ Class Attribute

In the Python code below, we print the name of the class using the __name__ class attribute

class Tutorialspoint:
   'Welcome to Tutorialspoint Python'

   def __init__(self):
      print("The __init__ method")

# getting the name of the class using built-in __name__ class attribute
print(Tutorialspoint.__name__)

Output

Tutorialspoint

Example 4: __module__ Class Attribute

In the Python code below, we print the module of the class using the __module__ class attribute

class Tutorialspoint:
   'Welcome to Tutorialspoint Python'

   def __init__(self):
      print("The __init__ method")

# getting the module of the class using built-in __module__ class attribute
print(Tutorialspoint.__module__ )

Output

__main__

Example 5: __bases__ Class Attribute

In the Python code below, we print the bases of the class using the built-in __bases__ class attribute

class Tutorialspoint:
   'Welcome to Tutorialspoint Python'

   def __init__(self):
      print("The __init__ method")

# getting the bases of the class using built-in __bases__ class attribute
print(Tutorialspoint.__bases__)

Output

(<class 'object'>,)

Applying all the class attributes in a single program

Algorithm (Steps)

Following are the Algorithm/steps to be followed to perform the desired task −

• Create a parent class with the name Employee

• Create a variable and initiaize the variable with 0 for storing the employ count.

• Create an init constructor which accepts the name, and salary as arguments.

In Python, __init__ is one of the reserved methods. It is referred to as a constructor in object-oriented programming. When an object is created from the class and access is necessary to initialize the class's attributes, the __init__ function is called.

• Initialize the values of instance attributes

• Increment the employ count by 1

• Create a function with the name displayCount which prints the total employee count.

• Print the employ count by applying the (.) operator on the Employee class

• Create another function with the name displayEmployee and print name and salary.

• Create a child class with the name subEmployee which inherits properties from the parent Employee class

• Use __doc__ class attribute, to print the Employee class with documentation

• Use __name__ class attribute, to print the name of the Employee class

• Use the __module__ class attribute, to print the module of the Employee class

• Use __dict__ class attribute, to print the dictionary containing the Employee class namespace

• Use the __bases__ class attribute, to print all the base classes for the derived class.

Example

# Creating a parent class with the name Employee
class Employee:
   'Common base class for all employees'
   # initiaizing the variable with 0 for storing the employ count
   empCount = 0

   # init constructor which accepts the name, salary as arguments
   def __init__(self, name, salary):

      # Initialize the values of instance attributes
      self.name = name
      self.salary = salary

      # incrementing the employ count by 1
      Employee.empCount += 1

   # displayCount () which prints the total employ count
   def displayCount(self):
      print("Total Employee :",Employee.empCount)

   # creating another function i.e, displayEmployee
   def displayEmployee(self):
      print ("Name : ", self.name, ", Salary: ", self.salary)

# creating child class with the name subEmployee inheriting properties
# from the parent Employee class
class subEmployee(Employee):
   'Derived class for Base - Employee Class'

# printing Employee class with documentation using __doc__ class attribute
print("Employee class documentation using the __doc__ attribute:\n", Employee.__doc__)

# printing the name of the Employee class using __name__ class attribute
print("Name of the class using the __name__ attribute:\n", Employee.__name__)

# printing the module of the Employee class using __module__ class attribute
print("Module of the class using the __module__ attribute:\n", Employee.__module__)

# printing the dictionary containing the Employee class namespace
# using __dict__ class attribute
print("Dictionary containing the Employee class namespace using the __dict__ attribute:\n", Employee.__dict__)

# printing all the base classes for the derived class using __bases__ class attribute
print("Base classes of subEmployee class using the __bases__ attribute:\n", subEmployee.__bases__)

Output

Employee class documentation using the __doc__ attribute:
Common base class for all employees
Name of the class using the __name__ attribute:
Employee
Module of the class using the __module__ attribute:
__main__
Dictionary containing the Employee class namespace using the __dict__ attribute:
{'__module__': '__main__', '__doc__': 'Common base class for all employees', 'empCount': 0, '__init__': <function Employee.__init__ at 0x7f9532090050>, 'displayCount': <function Employee.displayCount at 0x7f95320900e0>, 'displayEmployee': <function Employee.displayEmployee at 0x7f9532090170>, '__dict__': <attribute '__dict__' of 'Employee' objects>, '__weakref__': <attribute '__weakref__' of 'Employee' objects>}
Base classes of subEmployee class using the __bases__ attribute:
(<class '__main__.Employee'>,)

Conclusion

We learned all five built-in class attributes with an example from this article. We also demonstrated how these five built-in class attributes are used in practice by using two classes.

Vikram Chiluka

Updated on: 22-Sep-2022

15K+ Views

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