Python vars() Function

The vars() function returns the __dict__ attribute of an object. This is usually a dictionary containing all the writable attributes of the object. It’s useful when you want to inspect or work with an object's internal namespace.

Syntax

vars([object])

Parameters:

• object (optional) – The object whose __dict__ attribute you want to access. If no argument is provided, it returns the dictionary of the local symbol table.

Returns:

• A dictionary representing the __dict__ attribute of the object or the current local symbol table if no argument is given.

Example 1: Using vars() on a Class Instance

class Student:
    def __init__(self, name, grade):
        self.name = name
        self.grade = grade

s = Student("Alice", "A")
print(vars(s))

{'name': 'Alice', 'grade': 'A'}

Why? Because vars(s) returns the dictionary of attributes of the s object.

Example 2: Using vars() Without Arguments

x = 10
y = "Hello"
print(vars())

{'x': 10, 'y': 'Hello', ...}

This shows the local symbol table as a dictionary. It's useful for debugging or introspection.

Use Case: When to Use vars()?

• To inspect the attributes of an object (e.g., class instances)
• For debugging and exploring local/global scope contents
• When dynamically working with attributes and values

What if the Object Doesn’t Have __dict__?

If you pass an object that doesn’t have a __dict__ attribute, Python raises a TypeError.

print(vars(42))

TypeError: vars() argument must have __dict__ attribute

Interview Tip

Understanding vars() helps when you're dealing with object serialization, debugging tools, or custom class inspection.

Summary

• vars() shows the __dict__ of an object (if present).
• Without arguments, it shows the local symbol table.
• Useful for introspection, debugging, and meta-programming.

Practice Problem

Create a class Book with attributes title and author. Create an object and print all its attributes using vars().

class Book:
    def __init__(self, title, author):
        self.title = title
        self.author = author

b = Book("Python 101", "John Doe")
print(vars(b))