Isinstance() Function in Python

In Python, the isinstance() function is used to check if an object is an instance of a specific class.

Syntax

isinstance(object, class)

The function takes two parameters:

• The object you want to check.
• The class you want to verify against.

It returns a boolean value:

• True: If the object is an instance of the specified class.
• False: If the object is not an instance of the specified class.

A Practical Example

Here’s a simple script where I define two classes.

I then create an instance of the first class (Classe1) and assign it to the variable var.

1. class Classe1(object):
2. def metodo1(self):
3. print('A')
4. class Classe2(object):
5. def metodo1(self):
6. print('B')
7. var = Classe1()

Next, I use the isinstance() function to determine if var is an instance of Classe1.

The function returns True as expected:

>>> isinstance(var, Classe1)
>>> True

This confirms that var is indeed an instance of Classe1.

Now, let’s check if var is an instance of the second class, Classe2.

>>> isinstance(var, Classe2)
>>> False

Here, the function returns False, as var is not an instance of Classe2.

And so on.