PCAP-31-03 4.3 Equip a Class with Methods PCAP-31 Practice Questions (Page 5)

Questions 21–25

1. 21expert · hard

   A developer is creating a `Logger` class with a method `log` that should write a message to a file. The method needs to access the `file_path` attribute of the instance. Which method definition correctly declares the method and accesses the attribute?

   • Adef log(self, message): with open(self.file_path, 'a') as f: f.write(message)
   • Bdef log(self, message): with open(file_path, 'a') as f: f.write(message)
   • Cdef log(self, message): with open(self.file_path, 'a') as f: f.write(message) return True
   • Ddef log(message): with open(self.file_path, 'a') as f: f.write(message)
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2. 22expert · hard

   A `Car` class has a method `drive` that takes a distance and updates the `odometer` attribute. A user creates two instances `car1` and `car2`. They call `car1.drive(100)`. Which statement is true about the `odometer` attribute?

   • AThe `odometer` attribute is updated to 100 for `car1`, but `car2` will get an error.
   • BThe `odometer` attribute is not updated because `self` is not used.
   • COnly `car1.odometer` is updated to 100; `car2.odometer` remains unchanged.
   • DBoth `car1.odometer` and `car2.odometer` are updated to 100.
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4. 23expert · hard

   A `User` class has a method `change_password` that must validate the new password using a `validate_password` method, and if valid, update the `password` attribute. Which implementation correctly uses `self` to call the validation method and update the attribute?

   • Adef change_password(self, new_password): if validate_password(new_password): self.password = new_password
   • Bdef change_password(self, new_password): if self.validate_password(new_password): password = new_password
   • Cdef change_password(self, new_password): if self.validate_password(new_password): self.password = new_password else: print('Invalid')
   • Ddef change_password(self, new_password): if self.validate_password(new_password): self.password = new_password
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5. 24application · medium

   In a `ShoppingCart` class, the `add_item` method needs to update the total price and also log the addition. The `log` method is defined in the same class. How should `add_item` call `log` to ensure it uses the current instance's data?

   • Aself.log(self, item, price)
   • BCart.log(item, price)
   • Clog(item, price)
   • Dself.log(item, price)
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6. 25expert · hard

   A developer is explaining to a team why a method defined in a class must always have `self` as its first parameter. Which reason is most accurate?

   • ABecause methods are always called with an explicit instance argument.
   • BBecause Python automatically passes the instance as the first argument when the method is called on an instance.
   • CBecause methods cannot access instance attributes without `self`.
   • DBecause `self` is a reserved keyword in Python.
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