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Explore the differences between old-style and new-style classes in Python. Learn when you should inherit from `object` in your classes.
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Understanding Class Inheritance in Python: Do You Need to Inherit from object?

When working with Python, developers often encounter scenarios in which they need to define classes for their code. A common question arises: Do I need to inherit from the object class in my Python classes? While this might seem like a trivial issue, it actually pertains to a fundamental aspect of class architecture in Python, especially when considering different versions of the language. In this guide, we'll break down the necessity of inheritance from object, clarifying when and why it matters.

The Basics of Class Definition

In Python, you can define a class in several ways. Here are two common examples:

Old-style class in Python 2:

[[See Video to Reveal this Text or Code Snippet]]

New-style class in Python 2 and valid in Python 3:

[[See Video to Reveal this Text or Code Snippet]]

As you can see, one class (NoObj) is defined without explicitly inheriting from object, while the other (Obj) does. This leads us to discuss the differences between these approaches.

The Difference Between Old-style and New-style Classes

Old-style Classes (Python 2)

Definition: Classes created without inheriting from object.

Limitations: They lack certain features available in new-style classes, such as:

Descriptors

super() support for method resolution

A unified namespace for attributes

New-style Classes (Python 2 and 3)

Definition: Classes that explicitly inherit from object or are declared in the fashion supported in Python 3.

Benefits:

Unified Model: They unify the type and class hierarchy, making Python's object model more consistent.

Method Resolution Order (MRO): They use a more predictable method resolution order, useful in complex hierarchies.

Advanced Features: New-style classes support additional features like properties and static methods.

Python 3's Simplification

If you're using Python 3, the situation simplifies even further. In Python 3:

Class Declaration:

class Foo: is equivalent to class Foo(): and class Foo(object):.

This means any of the above will create a new-style class. Therefore, in Python 3, you can comfortably use classes without worrying about the impacts of the old-style declaration.

Conclusion

To summarize:

In Python 2, always inherit from object to create new-style classes, and avoid creating old-style classes altogether.

In Python 3, you don’t need to worry about inheriting from object; using a simple class declaration suffices as they all behave the same way.

Ultimately, understanding these distinctions can help you write cleaner, more efficient code. It’s generally a good practice to adopt new-style class patterns, as they are robust and equipped with the latest language features.

Understanding these nuances in class inheritance will allow you to make better-informed decisions in your development journey.