30+ Python Interview Questions And Answers

GIL stands for Global Interpreter Lock which is a mutex that protects access to Python objects, preventing multiple threads from executing Python bytecodes at once. This lock is necessary because CPython's memory management is not thread-safe.

A decorator is a design pattern in Python that allows a user to add new functionality to an existing object without modifying its structure. Decorators are usually called before the definition of a function you want to decorate.

 @my_decorator
def my_function():
    pass

A shallow copy creates a new object, but inserts references into it to the objects found in the original. In contrast, a deep copy creates a new object and recursively copies all the objects it finds. As a result, the two objects are independent.

 import copy
shallow = copy.copy(original)
deep = copy.deepcopy(original)

The 'with' statement is used for resource management and exception handling. It ensures that resources like file streams are properly cleaned up after use, even if an error occurs.

 with open('file.txt', 'r') as file:
    data = file.read()

Python uses a form of automatic memory management known as garbage collection, which relies on reference counting and a cyclic garbage collector to clean up unreachable objects.

You can use the Python debugger (pdb) to debug a program. It provides interactive debugging tools such as setting breakpoints, stepping through code, inspecting variables, and more.

 import pdb
pdb.set_trace()

*args is used for passing a variable number of non-keyword arguments, and **kwargs allows passing a variable number of keyword arguments to a function.

 def func(*args, **kwargs):
    pass

Encapsulation is accomplished by making attributes or methods private (preceding the name with an underscore).

 class MyClass:
    def __init__(self):
        self.__private_attr = 42
    
    def get_private_attr(self):
        return self.__private_attr

Generators are a special type of iterators that generate values on the fly, saving memory. They are created using the 'yield' statement instead of 'return'. When called, it resumes from where it left off.

 def my_generator():
    yield 1
    yield 2
    yield 3

It will print 'End of function' due to the finally block, then it will print 5 which is the output of the function add.

A metaclass in Python is a class of a class that defines how a class behaves. A class is an instance of a metaclass. By default, Python uses type as the metaclass from which all new classes are created.

Monkey patching refers to modifying or extending the behavior of libraries or classes at runtime without altering the original code.

The map function applies a given function to each item of an iterable (e.g., list), returning a map object which can be converted to a list for results.

 def square(num):
    return num ** 2
nums = [1, 2, 3, 4]
squared = map(square, nums)

@classmethod takes the class as an implicit first argument and acts on it, @staticmethod doesn’t take any implicit first arguments and thus behaves like a regular function defined inside a class, while instance methods take the instance as the first argument (self) and act upon instance variables.

List slicing is a method for extracting specific portions of a list by defining a start and end index, and optionally a step: list[start:end:step].

 my_list = [1, 2, 3, 4, 5]
sliced = my_list[1:4]