Decorator and Context Manager simple examples

.py

def decorator(f):
    @functools.wraps(f)
    def wrapper(*args, **kwargs):
        print('Wrapping')
        return f(*args, **kwargs)
    return wrapper
    
@decorator
def f():
    print('Function f')
    
@contextlib.contextmanager
def f2():
    print('Init')
    yield
    print('Finish')
    
from contextlib import contextmanager

@contextmanager
def db_transaction(connection):
    cursor = connection.cursor()
    try:
        yield cursor
    except:
        connection.rollback()
        raise
    else:
        connection.commit()

0.py

class FileContext:
    def __init__(self, f):
        self.file = open(f)
        
    def __enter__(self):
        return self.file

    def __exit__(self, exc_type, exc_value, traceback):
        self.file.close()
        print(traceback)
        
class File(object):
    def __init__(self, file_name, method):
        self.file_obj = open(file_name, method)
    def __enter__(self):
        return self.file_obj
    def __exit__(self, type, value, traceback):
        self.file_obj.close()
        
from contextlib import contextmanager

@contextmanager
def open_file(name):
    f = open(name, 'w')
    yield f
    f.close()