PCAP Object-Oriented Programming Practice Question

Answer analysis

Option-by-option breakdown

For each option: why learners choose it and why it is or isn't the right answer here.

• ✗

  Class names should be written in snake_case per PEP 8.

  Why it's wrong here

  PEP 8, the official Python style guide, specifies that class names should use CapWords (also called CamelCase) notation, such as MyClass, not snake_case. snake_case is reserved for function names, variables, and module attributes. Using snake_case for a class name violates the widely accepted convention and reduces readability for other Python developers.

• ✓

  Class variables are shared among all instances.

  Why this is correct

  Class variables are bound to the class namespace rather than to individual instances, so every instance shares the same variable. If the variable is reassigned on an instance, that creates a separate instance-level attribute that shadows the shared class variable, but the class variable itself remains unchanged for other instances. This shared behavior is a fundamental distinction from instance attributes, which are defined inside __init__ or other methods.

• ✗

  Private attributes (starting with __) cannot be accessed outside the class.

  Why it's wrong here

  Attributes with double leading underscores are not truly private; they are name-mangled at compile time to _ClassName__attribute to prevent accidental name collisions in subclasses. This mangling is deterministic and can be circumvented by referencing the mangled name from outside the class. Therefore, saying they cannot be accessed at all is false—they are simply hidden by convention and transformation.

• ✗

  __init__ is the constructor of a class.

  Why it's wrong here

  In Python, __init__ is the instance initializer, not the constructor, because it is called after the instance object already exists. The actual constructor is __new__, a static method that allocates and returns a new instance; __init__ then receives that instance to set up its state. Mislabeling __init__ as the constructor overlooks the distinct roles these two methods play in object creation.

• ✓

  Instance methods must have 'self' as the first parameter.

  Why this is correct

  Instance methods are defined inside a class and automatically receive the instance as their first argument; by convention this parameter is named self, but the name itself is not syntactically required. When you call obj.method(...), Python passes obj as the first argument to the method, so it must be able to access the instance's attributes. This is what distinguishes an instance method from a static method, which receives no automatic instance reference.

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