Useful Functions

isinstance()

The isinstance() (is instance) is a Python built-in function that checks object is an instance of a certain class and return the bool value (True or False). This function takes 2 arguments: instance and class:


              12
            
print(isinstance(662, int))
print(isinstance(25.3, int))

You can use this function to check your instances:


              123456
            
class User:
  pass

user = User()

print(isinstance(user, User))

issubclass()

The issubclass() (is subclass) is a Python built-in function that checks class is a Child of another class:


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class First:
    pass

class Second(First):
    pass

class Third(Second):
    pass

print(issubclass(Second, First))
print(issubclass(Third, First))

The issubclass() function works with classes only. If you want to check the instance, use the type() function inside the issubclass():


              123456789
            
class A:
    pass

class B(A):
    pass

instance = B()

print(issubclass(type(instance), A))

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Section 2. Chapter 6

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Course Content

In-Depth Python OOP