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Python issubclass() Function

How to use Python's issubclass() function to check if a class is a subclass of another class, type, or tuple of classes with practical examples.

The issubclass() function returns True if the specified object is a subclass of the specified object, otherwise False.

Syntax

issubclass(class, classinfo)

issubsclass() Parameters

Python issubsclass() function parameters:

Parameter Condition Description
class Required The class to be checked.
classinfo Required The class, type, or a tuple of classes/types against which the class is checked.

issubsclass() Return Value

Python issubsclass() function returns:

  • True if class is subclass of a class, or any element of the tuple
  • False otherwise

Examples

Example 1: Checking for Built-in Class Hierarchy with issubclass() function

Let's check for built-int class hierarchy:

print('bool is the subclass of int: ', issubclass(bool, int))    # Output: True
print('float is the subclass of int: ', issubclass(float, int))  # Output: False

output

bool is the subclass of int: True
float is the subclass of int: False

Example 2: Checking for Custom Class Hierarchy

Let's check for Custom Class Hierarchy:

class Person:
    pass

class Employee(Person):
    pass

class Employer(Person):
    pass

print('Employee is a subclass of Person: ', issubclass(Employee, Person))     # Output: True
print('Employer is a subclass of Person: ', issubclass(Employer, Person))     # Output: True
print('Employer is a subclass of Employee: ', issubclass(Employer, Employee)) # Output: False

output

Employee is a subclass of Person:  True
Employer is a subclass of Person:  True
Employer is a subclass of Employee:  False

Example 3: Checking for Multiple Class Hierarchies

Let's check for Multiple Class Hierarchies:

class Polygon:
    pass

class Triangle(Polygon):
    pass

print('Triangle is a subclass of Polygon: ', issubclass(Triangle, Polygon))                 # Output: True
print('Triangle is a subclass of list: ', issubclass(Triangle, list))                       # Output: False
print('Triangle is a subclass of list or Polygon: ', issubclass(Triangle, (list, Polygon))) # Output: True

output

Triangle is a subclass of Polygon:  True
Triangle is a subclass of list:  False
Triangle is a subclass of list or Polygon:  True

Example 4: Checking if a Class is a Subclass of Itself

Let's check if a Class is a Subclass of itself:

class MyClass:
    pass

print('MyClass is subclass of MyClass: ', issubclass(MyClass, MyClass))  # Output: True

output

MyClass is subclass of MyClass:  True
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