What Do self.name, self.x, and self.num Mean in Python Classes?

1. Introduction

Hello, I am a Python enthusiast. Recently a member asked why some code uses self.name = name, why some __init__ methods can use self.x and self.y without explicit parameters, and what self.num = x means.

Question examples (images):

2. Explanation

The assignment self.name = name stores the value passed as the parameter name into the instance attribute name, allowing the object to retain that value for later use.

When an attribute is defined directly in the class without being passed as a parameter, it is still accessed via self because it belongs to the instance; self.x and self.y refer to class‑level variables.

Similarly, self.num = x assigns the external variable x to the instance attribute num, making it available throughout the class.

3. Conclusion

This article clarified a common Python basics question, providing clear explanations and code examples to help readers understand instance attributes and the use of self in class definitions.