Advanced OOP — Series 3

Preview — 3 of 10 questions

What is the output of the following code?

javascript

class LoggingMixin:
    def save(self):
        print("logging save")
        super().save()

class ValidationMixin:
    def save(self):
        print("validating save")
        super().save()

class Base:
    def save(self):
        print("base save")

class Document(LoggingMixin, ValidationMixin, Base):
    pass

Document().save()

Alogging save, validating save, base save

Bbase save, validating save, logging save

Clogging save, base save

Dlogging save

What is the output of the following code?

javascript

class Meters:
    def __init__(self, value):
        self.value = value
    def __eq__(self, other):
        if not isinstance(other, Meters):
            return NotImplemented
        return self.value == other.value

class Plain:
    pass

m = Meters(5)
p = Plain()
print(m == p)
print(m == 5)

ANotImplemented, NotImplemented

BFalse, False

CTypeError: '==' not supported between instances of 'Meters' and 'Plain'

DTrue, False

What happens when the following code runs?

javascript

class Buggy:
    def __setattr__(self, name, value):
        self.data = value

try:
    b = Buggy()
    b.x = 5
except RecursionError:
    print("RecursionError")

AAttributeError: 'Buggy' object has no attribute 'data'

BNo error — b.x ends up holding 5, and b.data is untouched

CRecursionError

DNo error — b.data ends up holding 5

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