python_syntax_contextlib

gistfile1.txt

# https://docs.python.org/3/library/contextlib.html
	
from contextlib import contextmanager 
class MessageWriter(object):
  def __init__(self, filename):
    self.file_name = filename

  @contextmanager
  def open_file(self):
    try:
      file = open(self.file_name, 'w')
      yield file # Note you're not returning here. You 'yield' instead.
    finally:
      file.close()
      
message_writer = MessageWriter('hello.txt')
with message_writer.open_file() as my_file:
  my_file.write('hello world')