Is it possible to declare more than one variable using a with
statement in Python?
Something like:
from __future__ import with_statement
with open("out.txt","wt"), open("in.txt") as file_out, file_in:
for line in file_in:
file_out.write(line)
... or is cleaning up two resources at the same time the problem?
It is possible in Python 3 since v3.1 and Python 2.7. The new with
syntax supports multiple context managers:
with A() as a, B() as b, C() as c:
doSomething(a,b,c)
Unlike the contextlib.nested
, this guarantees that a
and b
will have their __exit__()
's called even if C()
or it's __enter__()
method raises an exception.
You can also use earlier variables in later definitions (h/t Ahmad below):
with A() as a, B(a) as b, C(a, b) as c:
doSomething(a, c)