Basic indexing
Input
IndexableList([10, 20, 30])[1]
Output
20
Index 1 returns the second element, 20.
Full lesson preview
Make Objects Indexable with __getitem__
Learn to implement __getitem__ so instances behave like sequences with integer indexing, including negative indices.
Python practice15 minMagic Methods & Operator OverloadingIntermediateLast updated April 11, 2026
Problem statement
You will implement a lightweight sequence wrapper class named IndexableList that stores a Python list internally and allows consumers to access elements using square-bracket indexing (obj[index]).
Requirements:
- Support integer indices (both positive and negative) in __getitem__.
- For invalid integer indices (out of range), raise IndexError (same semantics as Python lists).
- Type-check the index and raise TypeError for non-integer indices.
Do not implement slicing or other behaviors in this exercise — only integer indexing is required.
Task
Implement a class that supports integer indexing (including negative indices) via the __getitem__ magic method.
Examples
Input format
A single expression that evaluates to an element access, e.g. IndexableList([a, b, c])[index].
Output format
The value retrieved by __getitem__; tests compare str(returned_value).
Constraints
- Only integer indices are required (positive and negative).
- For non-integer indices, raise TypeError.
- For out-of-range indices, raise IndexError.
Samples
Sample 1
Input
IndexableList(['x', 'y', 'z'])[0]
Output
x
Returns the first element 'x'. Strings are compared without quotes in the test harness.