from abc import ABC, abstractmethod class DataProcessor(ABC): def __init__(self, data): self.data = data @abstractmethod def clean(self): pass def process(self): cleaned_data = self.clean() return sum(cleaned_data) class ListProcessor(DataProcessor): def clean(self): cleaned = [] for x in self.data: if isinstance(x, (int, float)): cleaned.append(x) return cleaned class AveragingProcessor(ListProcessor): def process(self): cleaned = self.clean() return sum(cleaned) / len(cleaned) dp = ListProcessor([1, 2, "a", 3]) ap = AveragingProcessor([10, None, 20, 30, "skip"]) print(dp.process()) print(ap.process()) What will happen when the above code is executed? Select all correct statements. Incorrect selections will deduct points from your score.

Question

BlackTom AI · Accepted Answer

To tackle this question, I’ll walk through what each part of the code does and then evaluate each statement against that behavior.
Option a: The class AveragingProcessor inherits both clean() and process() from ListProcessor. In reality, AveragingProcessor defines its own process method, overriding the one it would otherwise inherit. Therefore it does not inherit the base class’s process implementation as-is. This makes option a incorrect.
Option b: ListProcessor is instantiable after overriding clean() without overriding process(). Indeed, ListProcessor provides its own clean() method, but does not override process(), so it uses the process() method from DataProcessor that calls self.clean() and sums the resulting cleaned data. Since clean() is defined in ListProcessor, dp = ListProcessor([1, 2, "a", 3]) can be instantiated and dp.process() will work (producing 6). This statement is correct.
Option c: The code will raise a TypeError when calling dp.process(). As reasoned above, dp.process() executes successfully: it calls clean(), obtains [1, 2, 3], and returns 6. There is no TypeError raised here, so option c is incorrect.
Option d: The method clean() will raise a ValueError if the input list contains None. The implementation uses isinstance checks for int or float, so None is simply skipped and not included in the cleaned list. No error is raised for None; the method silently ignores non-numeric items. Thus option d is incorrect.
Option e: The @abstractmethod decorator prevents instantiating DataProcessor directly. Since DataProcessor has an abstractmethod clean, attempting to instantiate DataProcessor would raise a TypeError, so this statement is correct.
In summary, the statements that are true are: option b and option e. The rest describe behaviors that do not align with how the code actually executes.

FIT9136 Introduction to Python programming - S2 2025

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