I’m the main contextlib maintainer, and contextlib2.ContextStack is a new API I have created and published on PyPI that will hopefully provide the dynamic context management benefits of nested() without being anywhere near as error-prone. The “open a data driven number files at the same time” use case is actually the recurring example I use in the documentation (http://contextlib2.readthedocs.org/en/latest/index.html#contextlib2.ContextStack)

with open(x) as u, open(y) as w:
pass

with open(‘file1′) as f,\
open(‘file2) as g:
…

with open(‘in.txt’) as infile, open(‘out.txt’, ‘w’) as outfile:

1. If an error happens while closing a file, all next files will be left open
2. If opening one of the file fails, all files previously opened will be left open

You should also close the files in the inverse order than the one you opened them in, but that’s a minor issue.

Overall, the original code should be left as-is when using Python 2.5 or 2.6. For Python 2.7-only code or Python 3 code, `with` can be used with multiple managers out of the box:

with open(path1, ‘r’) as file1, open(path2, ‘r’) as file2:
# stuff.

See examples at the bottom of the “with statement” section: http://docs.python.org/reference/compound_stmts.html#with

with opens(‘/tmp/foo.py’, (‘/tmp/bar.py’, ‘w’)) as (f1, f2):
f2.write(f1.read())

Something like the following would do the trick:

import contextlib

@contextlib.contextmanager
def opens(*fnames):
fs = []
for x in fnames:
if not isinstance(x, tuple):
x = (x, ‘r’)
fs.append(open(*x))
try:
yield fs
finally:
for f in fs:
f.close()

[python]
from contextlib import nested
with nested(open(‘file1′), open(‘file2′)) as (f1, f2):
f1.readlines()
f2.readlines()
[/python]

with open(‘one.file’) as file_one, open(‘second.file’) as file_second:
print(file_one)
print(file_second)