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.

• ✓

  def my_method(cls): pass my_method = classmethod(my_method)

  Why this is correct

  This is a valid, if less common, manual application of the classmethod() built-in. The module-level function is defined with a first parameter named cls, and then classmethod(my_method) wraps that function in a classmethod descriptor before assigning it back to the same name. From that point on, accessing the attribute on the class or on an instance binds the class object as the first argument, exactly as the @classmethod decorator would do at class creation time.

• ✗

  class MyClass: def my_method(cls): pass

  Why it's wrong here

  Inside a class body, a bare def creates an instance method descriptor, not a class method; the name cls does not change that binding behavior. When the method is called on an instance, Python automatically passes the instance as the first argument, so cls receives the instance object, and when accessed through the class it remains an unbound function requiring an explicit class argument. Without the @classmethod decorator or a classmethod(my_method) assignment, the method lacks the descriptor logic needed to bind the class itself.

• ✗

  def my_method(self): pass

  Why it's wrong here

  This code snippet is simply a plain function definition with a self parameter; it does not define a class and it does not create any binding behavior. If this function were later placed inside a class body unchanged, it would be an ordinary instance method, receiving an instance as its first argument. It cannot behave as a class method because nothing marks it with @classmethod or passes it through classmethod(), so the class object is never implicitly supplied.

• ✗

  @staticmethod def my_method(cls): pass

  Why it's wrong here

  The @staticmethod decorator intentionally strips the descriptor binding behavior: the method becomes an ordinary function stored in the class namespace, so neither the class nor an instance is passed automatically. Even though the parameter is named cls, that name is only a convention and has no effect on how arguments are supplied; the caller must explicitly pass the class if it is needed. Therefore this defines a static method, not a class method, and any reference to cls will receive whatever explicit argument the caller provides, not the class.

• ✓

  @classmethod def my_method(cls): pass

  Why this is correct

  This is the canonical class method definition: the @classmethod decorator wraps the function in a classmethod descriptor, and whenever the method is accessed—whether through the class or an instance—the descriptor inserts the class object as the first positional argument. The parameter is conventionally named cls to make that binding explicit and readable. This declarative form is exactly equivalent at runtime to the manual classmethod() assignment shown in the correct alternate answer.

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