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The builtins

Python’s built-in functions, exceptions, and types live in the builtins namespace. Understanding this namespace clarifies what is always available without imports.

What is builtins?

builtins is a module automatically loaded by Python that contains: - core functions (len, print, range, …), - built-in types (int, list, dict, …), - built-in exceptions (ValueError, TypeError, …).

You normally use these names without qualification.

Inspecting

import builtins
dir(builtins)

This shows all names that are globally available.

Shadowing builtins

You can accidentally override built-ins:

list = [1, 2, 3]   # BAD

After this, list() no longer refers to the type.

Avoid shadowing built-in names.

Why this matters

Understanding builtins helps with: - debugging name conflicts, - reading unfamiliar code, - metaprogramming and introspection.

Key takeaways

  • Built-ins live in the builtins module.
  • They are always available without imports.
  • Avoid shadowing built-in names.