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HardPro challengePython

Descriptor Protocol — Validated Attribute

PythonMetaprogrammingDescriptors

Implement a PositiveNumber descriptor that:

  • Allows setting only positive numbers (> 0). Raises ValueError for zero or negatives.
  • Returns the stored value on get.
  • Stores values per-instance (not on the descriptor itself).
class Circle:
    radius = PositiveNumber()

c = Circle()
c.radius = 5    # OK
c.radius        # → 5
c.radius = -1   # raises ValueError

Implement solve(value) that creates a Circle, sets its radius = value and returns the radius. If value <= 0, return the string "error".

Sample tests

Test #1Positive value stored and returned
Input: [5]
Output: 5
Test #2Negative value raises ValueError
Input: [-1]
Output: "error"
Test #3Zero raises ValueError
Input: [0]
Output: "error"
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