Quick Check: Python Properties and Managed Attributes

Review

1. Which decorator turns a method into the getter for a property?

   @property creates a property whose getter is the decorated method.
2. Which decorator defines the setter for a property named balance?

   @balance.setter attaches a setter to the existing balance property.
3. What does del account.balance do when balance has a property deleter?

   del on a property calls the deleter when one is defined.
4. Why might a property use an attribute such as _value for storage?

   A backing attribute is a common implementation detail used by the property accessors.
5. When is a normal method often clearer than a property?

   A normal method is often clearer for an action or an operation that accepts arguments.
6. After a cached_property first calculates a value, what happens on a later lookup if the attribute has not been overwritten or deleted?

   cached_property writes the computed value to the instance. Subsequent attribute reads find that value and do not call the getter until the attribute is removed.
7. A cached count was read, then the list used to calculate it changed. What should you do before the next read if you need the updated count?

   Deleting the stored attribute exposes the cached_property descriptor again, so the next lookup recalculates using the current source data.