Object-Oriented Programming for Data Modeling PCAD-31 Practice Questions (Page 1)

Questions 1–5

1. 1foundation · easy

   What is the purpose of prefixing an attribute name with two underscores (e.g., `__balance`) in a Python class?

   • ATo indicate the attribute is private and should not be accessed directly from outside the class
   • BTo make the attribute immutable
   • CTo make the attribute accessible only to subclasses
   • DTo make the attribute a class attribute
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2. 2foundation · easy

   Which module provides the `copy` and `deepcopy` functions in Python?

   • Adeepcopy
   • Bclone
   • Cobject
   • Dcopy
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4. 3foundation · easy

   What is a key advantage of using a `namedtuple` over a regular tuple?

   • AIt automatically provides methods for data analysis
   • BIt uses less memory than a regular tuple
   • CIt allows field access by name, improving code readability
   • DIt is mutable, allowing field values to be changed
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5. 4foundation · easy

   Why must `__hash__` be consistent with `__eq__`?

   • ATo ensure that objects are copied correctly
   • BTo ensure that equal objects have the same hash value, which is required for correct behavior in sets and dictionaries
   • CTo ensure that objects are sorted correctly
   • DTo ensure that objects are displayed correctly
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6. 5application · medium

   A data model represents an Order that contains multiple OrderLine items. Each OrderLine has a product and a quantity. The analyst needs to model this so that an Order owns its OrderLines, and when an Order is deleted, its OrderLines are also removed. Which relationship type should be used?

   • AAggregation — the Order holds references to OrderLine objects that exist independently.
   • BAssociation — a loose coupling where Order and OrderLine reference each other but neither owns the other.
   • CComposition — the Order creates and owns its OrderLine objects, and they cannot exist without the Order.
   • DInheritance — OrderLine is a subclass of Order.
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