On 01/24/2017 02:35 PM, Ethan Furman wrote:
On 01/24/2017 01:31 PM, This Wiederkehr wrote:
having a class definition:
class Test():
@classmethod
def __enter__(cls):
pass
@classmethod
def __exit__(cls, exception_type, execption_value, callback):
pass
now using this as a contextmanager does not work, even though Test is an
object and has the two required methods __enter__ and __exit__.
It is not working because you are trying to use the class itself, and not it's
instances, as a context manager (which also means you don't need classmethod):
Wrong:
with Test:
Correct:
with Test():
I am asking because I'd like to implement the clean up behaviour for
multiple instances directly into the class:
with Test:
testinstance1 = Test()
testinstance2 = Test()
# on context exit Test.__exit__ should take care on cleaning up
testinstance1 and testinstance2.
You might be able to make this work with a custom type (aka using a custom
metaclass) -- but that could be a bunch of work.
Okay, here's the easy part:
--- 8< ----------------------------
class TestType(type):
def __enter__(cls):
pass
def __exit__(cls, *args):
pass
class Test(metaclass=TestType):
pass
with Test:
print('worked!')
--- 8< ----------------------------
Let us know how it turns out.
--
~Ethan~
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