Day 8: Forgetting self in Class Methods

🐍 Python Mistakes Everyone Makes ❌

Day 8: Forgetting self in Class Methods

When learning object-oriented programming in Python, forgetting self is one of the most common (and confusing) mistakes.

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❌ The Mistake

class Person:
      def greet():
          print("Hello")
p = Person()
p.greet()

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❌ Why this fails?

Because instance methods must accept self as the first parameter.

• When you call p.greet(), Python automatically passes the instance (p) to the method.

• Without self, Python doesn’t know where to put that argument, causing a TypeError.

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✅ The Correct Way

class Person:
     def greet(self):
           print("Hello")

p = Person()
p.greet()

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🧠 Simple Rule to Remember

• Instance methods → must have self

• self represents the object calling the method

• It allows access to instance variables and other methods

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✅ Key Takeaway

Always include self as the first parameter in instance methods.
It’s how Python connects methods to the object they belong to.