How Can I Open Multiple Files in Python with a Single `with open` Statement?

Context Managers for Opening Multiple Files in Python

Python's with open statement effectively manages file operations by automatically closing files when the with block exits. However, opening multiple files using successive with open statements introduces a challenge if you want to ensure all files can be written to.

Combining Multiple with open Statements

The syntax presented in the question, attempting to combine with open statements with the and keyword, is invalid. To achieve the desired functionality, Python 2.7 (or 3.1) and later versions introduced a change that allows you to simply separate multiple with open statements with commas:

with open('a', 'w') as a, open('b', 'w') as b:
    do_something()

This syntax correctly manages the context for multiple files, closing them when the with block exits.

Alternative for Variable Number of Files

In cases where you may need to open a variable number of files, the contextlib.ExitStack class provides a solution starting from Python 3.3:

with ExitStack() as stack:
    files = [stack.enter_context(open(fname)) for fname in filenames]
    # Do something with "files"

Sequential vs. Simultaneous File Opening

It's important to note that opening multiple files simultaneously is not always ideal. In most cases, processing files sequentially is a more common approach:

for fname in filenames:
    with open(fname) as f:
        # Process f

This approach avoids potential issues related to resource management and file locking.

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