Area of a 3x4 rectangle
Input
Rectangle(3, 4).area
Output
12
area computes width * height = 3 * 4 = 12
Full lesson preview
Create a Read-Only Computed Property
Implement a computed property that provides a read-only view derived from internal state.
Python practice15 minEncapsulation & Access PatternsIntermediateLast updated April 8, 2026
Problem statement
Implement a Rectangle class that stores width and height. Provide a read-only property area that returns width * height. Width and height should be validated in the constructor to be numeric (int or float, but not bool) and non-negative. The area property must be implemented using @property and should compute the result on access (no setter).
Task
Provide a computed read-only property using @property that computes a value from private attributes without allowing assignment.
Examples
Input format
A class Rectangle(width, height). Tests will construct rectangles and access the .area property in single-expression form.
Output format
Accessing .area returns the numeric area (int or float) as a value.
Constraints
width and height must be int or float (not bool) and >= 0. area has no setter and should compute width * height.
Samples
Sample 1
Input
Rectangle(2.5, 4).area
Output
10.0
Floating point width is supported; area is 2.5 * 4 = 10.0