In Python3 we can use multiple contexts in with statements. But is it possible to enter multiple contexts if they can't be constructed right away in the with statement? Is it possible to do something like this?
def files():
return open('a.txt', 'w'), open('b.txt', 'w')
with files():
pass
Or this:
files = open('a.txt', 'w'), open('b.txt', 'w')
with files:
pass
from contextlib import contextmanager
@contextmanager
def files():
with open('a.txt', 'w') as f1, open('b.txt', 'w') as f2:
yield f1,f2
maybe?
with files() as (f1,f2):
print(f1,f2)
f1,f2 in with files() as f1,f2, or the precedence isn't going to work the way you want.An example using contextlib.ExitStack:
from contextlib import ExitStack
def files(stack, *args):
return [stack.enter_context(open(f, "w")) for f in args]
with ExitStack() as stack:
f1, f2 = files(stack, "a.txt", "b.txt")
...
or without the wrapper
with ExitStack() as stack:
f1, f2 = [stack.enter_context(open(f, "w")) for f in ["a.txt", "b.txt"]]
...
However, when you know how many files are to be opened ahead of time (and it's a small number of files), the multiple manager form of the with statement as shown in Joran Beasley's answer is simpler.
contextlib.ExitStackas that's my gut feeling but I'm still not sure what the use case is...with open(...), open().... Maybe saving context into variable is not nice, but pattern with a function should be fairy safe.