File Handling

File handling refers to the creating, reading, writing and managing files using python.

File Modes

Some key point to know

1. To read entire file use f.read() or to read one line f.readline() or to read all lines file.readlines()
2. If file mode is used as w it will overwrite the existing content of the file, to only append the data at the end use a file mode.
3. Using context manager while dealing with files is recommended. with open(file, 'w') as f this syntax.

Exception Handling

Exception Handling is a mechanism used to handle runtime errors and prevent the program from terminating unexpectedly. Exception handling is implemented using try and expect block.

try:
	x = 1 / 0
	print(x)
expect Exception as e:
	print('Diving by zero')

Some important topics to know

1. *args and **kwargs

*args collects positional arguments into a tuple, while **kwargs collects keyword arguments into a dictionary.

def add(*args):
    return sum(args)

def employee(**kwargs):
	print(kwargs)


print(add(1, 2, 3, 4))
employee(name="Pranjal", role="Data Engineer")

# O/P
# 10
# { 'name': 'Pranjal', 'role': 'Data Engineer' }

2. Decorators

A Decorator is a function that modifies or extends the behavior of another function without changing its source code.
They are helpful for logging, authenticating, monitoring, performance tracking, retry mechanisms

def decorator(func):
    def wrapper():
        print("Before Function")
        func()
        print("After Function")
    return wrapper

@decorator
def greet():
    print("Hello")

greet()

3. @staticmethod vs @classmethod

Static methods are utility functions related to a class which can be called from class itself but cannot access class-level data , while class methods operate on class-level data through the cls parameter.

5. Multithreading vs Multiprocessing

Multithreading is running multiple threads inside the same process.
Multiprocessing is running multiple independent processes.