PCAP-31-03 4.6 Construct and Initialize Objects PCAP-31 Practice Questions (Page 4)

Questions 16–20

1. 16expert · hard

   A developer is refactoring a class that currently has __init__(self, name, age). The new requirement is that age should be optional, defaulting to 0. However, existing code calls the constructor with both arguments positionally. Which change will maintain backward compatibility?

   • AChange the signature to __init__(self, name, age=0)
   • BChange the signature to __init__(self, name, *args)
   • CChange the signature to __init__(self, age=0, name)
   • DChange the signature to __init__(self, name)
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2. 17expert · hard

   A developer is debugging a class where the __init__ method sets an attribute using self.data = data. However, after creating an instance, the attribute data is not accessible from outside the class. What is the most likely cause?

   • AThe instance is being garbage collected immediately.
   • BThe attribute name is misspelled in the __init__ method.
   • CThe attribute is being set as a class attribute instead of an instance attribute.
   • DThe __init__ method is not being called because the class has a custom __new__.
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4. 18expert · hard

   A developer is designing a base class that should not be instantiated directly, but subclasses should be able to define their own __init__. The base class has no __init__. What is the best way to prevent direct instantiation of the base class?

   • ADefine __init__ in the base class that raises an exception.
   • BDefine __init__ in the base class that does nothing.
   • CDo nothing; the default constructor will allow instantiation.
   • DUse a metaclass to prevent instantiation.
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5. 19expert · medium

   A developer is using a third-party class that has an __init__ method with a required parameter 'token'. The developer wants to create an instance but does not know the token value until runtime. Which approach is best?

   • ACreate the instance without the token and set the token attribute later.
   • BWait until the token is available, then create the instance with the token.
   • CUse a class method to create the instance after the token is known.
   • DModify the class to make the token optional.
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6. 20expert · medium

   A developer is creating a class with an __init__ method that has a parameter named 'self'. The developer wants to use a different name for the instance reference. Is this possible?

   • ANo, the first parameter must be named 'self'.
   • BYes, but only if the class is defined with a metaclass.
   • CYes, but it is not recommended because it would confuse other developers.
   • DNo, because the interpreter requires the name 'self'.
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