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09.contextlib.py
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83 lines (58 loc) · 1.3 KB
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class Query(object):
def __init__(self, name):
self.name = name
def __enter__(self):
print('Begin')
return self
def __exit__(self, exc_type, exc_value, traceback):
if exc_type:
print('Error')
else:
print('End')
def query(self):
print('Query info about %s...' % self.name)
with Query('Bob') as q:
q.query()
# Begin
# Query info about Bob...
# End
from contextlib import contextmanager
class Query(object):
def __init__(self, name):
self.name = name
def query(self):
print('Query info about %s...' % self.name)
@contextmanager
def create_query(name):
print('Begin')
q = Query(name)
yield q
print('End')
with create_query('Bob') as q:
q.query()
# Begin
# Query info about Bob...
# End
@contextmanager
def tag(name):
print("<%s>" % name)
yield
print("</%s>" % name)
with tag("h1"):
print("hello")
print("world")
# <h1>
# hello
# world
# </h1>
from contextlib import closing
from urllib.request import urlopen
with closing(urlopen('https://www.python.org')) as page:
for line in page:
print(line)
@contextmanager
def closing(thing):
try:
yield thing
finally:
thing.close()