How to efficiently modify multiple files in Python using the \"with open\" statement?

Opening Multiple Files with the "with open" Statement in Python

Modifying multiple files simultaneously raises the question of how to perform this operation efficiently while maintaining file integrity. Utilizing the "with open" statement along with context management offers a practical solution.

Using "with open" with Multiple Files

In Python versions 2.7 and above, the syntax has been revised to allow multiple file openings within a single "with open" statement:

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

This eliminates the need for nested "with" statements or the use of "contextlib.nested()."

Alternative Approaches

In rare instances where the number of files to be opened is variable, "contextlib.ExitStack" offers a flexible solution available in Python 3.3 and later:

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

However, sequential file processing is often more suitable, especially when dealing with a variable number of files:

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

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