Use context manager in lambda, how?

Question

How can I use a context manager in a lambda? Hacks accepted. Defer opinions about this being a bad usage of lambdas.

I know I can do this:

def f():
    with context():
        return "Foo"

But I would like to do something like this:

lambda: with context(): "Foo"

Answer 1

One possible workaround for getting lambdas working with a context manager is to make the context manager a ContextDecorator, then both with statements and lambda expressions will work because a lambda can use the decorator pattern instead.

Example

from contextlib import ContextDecorator


def f(x):
     """Just prints the input, but this could be any arbitrary function."""
     print(x)


class mycontext(ContextDecorator):
    def __enter__(self):
        f('Starting')
        return self

    def __exit__(self, *exc):
        f('Finishing')
        return False

with mycontext():
    f('The bit in the middle')

mycontext()(lambda: f('The bit in the middle'))()