Day 9:Overwriting built-in names

 

🐍 Python Mistakes Everyone Makes ❌

Day 9: Overwriting Built-in Names

One of the easiest mistakes to make in Python is accidentally overwriting built-in names like list, dict, or str.

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❌ The Mistake

list = [1, 2, 3]
numbers = list((4, 5, 6))

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❌ Why this fails?

Because list is a built-in type in Python.

When you assign a variable named list, you override Python’s built-in list() function.
After that, Python can no longer use list() as a constructor.

This often results in confusing errors like:

TypeError: 'list' object is not callable

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✅ The Correct Way

numbers_list = [1, 2, 3] 

numbers = list((4, 5, 6))
print(numbers)

✔ Built-in list() remains intact
✔ Code works as expected

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🧠 Simple Rule to Remember

• Never name variables after built-ins

• Common built-ins to avoid:

  1)list
  
  
  2)dict
  
  
  3)set
  
  
   4)str
  
  
   5)int 
  
  
  6)sum

Use descriptive names instead:

user_list
numbers_dict
total_sum

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✅ Key Takeaway

Overwriting built-ins doesn’t break Python immediately —
but it creates hard-to-debug errors later.

Avoiding this habit will make your code cleaner, safer, and more readable.