context managers

Question 1

context manager

Answer 1

with context_manager:
context_manager.__enter__()
body
context_manager.__exit__()

Question 2

context manager protocol

Answer 2

\_\_enter\_\_(self):   
\_\_exit\_\_(self,
     exc_type,
     exc_val,
     exc_tb
)

Question 3

__enter__() return …

Answer 3

context manager

Question 4

default behaviour with exceptions in with block

Answer 4

__exit__() propagates exeptions

Question 5

to propagates exceptions from with block …

Answer 5

__exit__() must return False

Question 6

standart library for working with context managers

Answer 6

contextlib

Question 7

context manager decorator

Answer 7

@contextlib.contextmanager
def my_context_manager():
    # 
    try:
        yield [value]
        # 
    except:

    raise

with my_context_manager() as x:

Question 8

multiple context managers

Answer 8

with cm1() as a, cm2() as b, … :