Python Advanced

Which keyword starts a class definition in Python?

• def
• class
• struct
• module

Answer explanation

Classes are defined using the 'class' keyword.

Which method is automatically invoked when a new instance is created?

• __new__
• __call__
• __init__
• __start__

Answer explanation

__init__ is the constructor called after an instance is created.

What does the 'self' parameter in instance methods refer to?

• Current class
• Instance object
• Parent class
• Global namespace

Answer explanation

'self' refers to the instance on which the method is called.

Which of these is an example of encapsulation?

• Using global variables
• Hiding attributes using name-mangling
• Multiple inheritance
• Using map/filter

Answer explanation

Encapsulation hides implementation details; name mangling (prefix __) limits external access.

How do you indicate a 'private' attribute by convention in Python?

• prefix with __
• suffix with _priv
• prefix with _
• use private keyword

Answer explanation

By convention a single underscore prefix (e.g., _attr) indicates 'protected' or internal use.

What is name mangling in Python?

• Encrypting names
• Compiler optimization
• Interpreter renaming __attr to _ClassName__attr
• Renaming modules

Answer explanation

Name mangling rewrites __attr as _ClassName__attr to reduce accidental access.

Which decorator defines a class method that receives the class instead of instance?

• @staticmethod
• @classmethod
• @property
• @abstractmethod

Answer explanation

@classmethod receives the class (cls) as the first argument.

Which decorator creates a method that does not receive instance or class automatically?

• @staticmethod
• @classmethod
• @instancemethod
• @bind

Answer explanation

@staticmethod creates a function placed in the class namespace but receives no implicit first argument.

What is method overriding?

• Providing multiple methods of same name in same class
• Redefining parent method in subclass
• Using same name for variables
• Calling a method twice

Answer explanation

Overriding replaces a parent class method with a subclass implementation.

Which built-in checks whether an object is an instance of a class or tuple of classes?

• type()
• isinstance()
• issubclass()
• hasattr()

Answer explanation

isinstance(obj, Class) returns True if obj is an instance of Class or its subclasses.