Non-empty cart is truthy
Input
bool(ShoppingCart([('apple', 2)]))
Output
True
The cart has a single item with quantity 2, so the cart is truthy.
Full lesson preview
Customize Truthiness with __bool__
Learn how to control an object's truth value by implementing __bool__ so instances behave naturally in boolean contexts.
Python practice15 minMagic Methods & Operator OverloadingIntermediateLast updated April 11, 2026
Problem statement
Implement the ShoppingCart class so that Python's bool() applied to an instance returns True when the cart contains at least one item with a positive quantity, and False otherwise. Items are represented as (name, quantity) pairs stored in a list. Your implementation should be robust to numeric quantities (ints or floats) and treat non-numeric quantities as zero.
Task
Implement a ShoppingCart class whose boolean truthiness reflects whether the cart contains any positive quantity items.
Examples
Input format
A single expression will be evaluated. For tests, bool() will be called on ShoppingCart instances constructed with a list of (name, quantity) tuples.
Output format
The expression should evaluate to a Python value whose string form is compared to the expected output.
Constraints
Quantities are expected to be non-negative numbers (int or float). Non-numeric quantities should be treated as zero. The __bool__ method must return a boolean.
Samples
Sample 1
Input
bool(ShoppingCart([('banana', 0), ('pear', 1.5)]))
Output
True
One item has a positive quantity (1.5), so the cart is truthy.