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import sys
def typename(t):
name = type(t).__name__
if sys.version_info < (2,5):
if name == 'classobj' and issubclass(t, MyException):
name = 'type'
elif name == 'instance' and isinstance(t, MyException):
name = 'MyException'
return "<type '%s'>" % name
class MyException(Exception):
pass
class ContextManager(object):
def __init__(self, value, exit_ret = None):
self.value = value
self.exit_ret = exit_ret
def __exit__(self, a, b, tb):
print("exit %s %s %s" % (typename(a), typename(b), typename(tb)))
return self.exit_ret
def __enter__(self):
print("enter")
return self.value
def no_as():
"""
>>> no_as()
enter
hello
exit <type 'NoneType'> <type 'NoneType'> <type 'NoneType'>
"""
with ContextManager("value"):
print("hello")
def basic():
"""
>>> basic()
enter
value
exit <type 'NoneType'> <type 'NoneType'> <type 'NoneType'>
"""
with ContextManager("value") as x:
print(x)
def with_pass():
"""
>>> with_pass()
enter
exit <type 'NoneType'> <type 'NoneType'> <type 'NoneType'>
"""
with ContextManager("value") as x:
pass
def with_return():
"""
>>> print(with_return())
enter
exit <type 'NoneType'> <type 'NoneType'> <type 'NoneType'>
value
"""
with ContextManager("value") as x:
return x
def with_break():
"""
>>> print(with_break())
enter
exit <type 'NoneType'> <type 'NoneType'> <type 'NoneType'>
a
"""
for c in list("abc"):
with ContextManager("value") as x:
break
print("FAILED")
return c
def with_continue():
"""
>>> print(with_continue())
enter
exit <type 'NoneType'> <type 'NoneType'> <type 'NoneType'>
enter
exit <type 'NoneType'> <type 'NoneType'> <type 'NoneType'>
enter
exit <type 'NoneType'> <type 'NoneType'> <type 'NoneType'>
c
"""
for c in list("abc"):
with ContextManager("value") as x:
continue
print("FAILED")
return c
def with_exception(exit_ret):
"""
>>> with_exception(None)
enter
value
exit <type 'type'> <type 'MyException'> <type 'traceback'>
outer except
>>> with_exception(True)
enter
value
exit <type 'type'> <type 'MyException'> <type 'traceback'>
"""
try:
with ContextManager("value", exit_ret=exit_ret) as value:
print(value)
raise MyException()
except:
print("outer except")
def with_real_lock():
"""
>>> with_real_lock()
about to acquire lock
holding lock
lock no longer held
"""
from threading import Lock
lock = Lock()
print("about to acquire lock")
with lock:
print("holding lock")
print("lock no longer held")
def functions_in_with():
"""
>>> f = functions_in_with()
enter
exit <type 'type'> <type 'MyException'> <type 'traceback'>
outer except
>>> f(1)[0]
1
>>> print(f(1)[1])
value
"""
try:
with ContextManager("value") as value:
def f(x): return x, value
make = lambda x:x()
raise make(MyException)
except:
print("outer except")
return f
def multitarget():
"""
>>> multitarget()
enter
1 2 3 4 5
exit <type 'NoneType'> <type 'NoneType'> <type 'NoneType'>
"""
with ContextManager((1, 2, (3, (4, 5)))) as (a, b, (c, (d, e))):
print('%s %s %s %s %s' % (a, b, c, d, e))
def tupletarget():
"""
>>> tupletarget()
enter
(1, 2, (3, (4, 5)))
exit <type 'NoneType'> <type 'NoneType'> <type 'NoneType'>
"""
with ContextManager((1, 2, (3, (4, 5)))) as t:
print(t)
class GetManager(object):
def get(self, *args):
return ContextManager(*args)
def manager_from_expression():
"""
>>> manager_from_expression()
enter
1
exit <type 'NoneType'> <type 'NoneType'> <type 'NoneType'>
enter
2
exit <type 'NoneType'> <type 'NoneType'> <type 'NoneType'>
"""
with GetManager().get(1) as x:
print(x)
g = GetManager()
with g.get(2) as x:
print(x)
def manager_from_ternary(use_first):
"""
>>> manager_from_ternary(True)
enter
exit <type 'type'> <type 'ValueError'> <type 'traceback'>
>>> manager_from_ternary(False)
enter
exit <type 'type'> <type 'ValueError'> <type 'traceback'>
In except
"""
# This is mostly testing a parsing problem, hence the
# result of the ternary must be callable
cm1_getter = lambda: ContextManager("1", exit_ret=True)
cm2_getter = lambda: ContextManager("2")
try:
with (cm1_getter if use_first else cm2_getter)():
raise ValueError
except ValueError:
print("In except")
|
