How to Improve File Handling with Multiple Open Statements in Python

In Python, the open() function is a versatile tool for file input and output. When working with multiple files, it's advantageous to utilize the with statement to ensure proper resource management.

Situation:

Consider a code snippet that reads names from a file and appends additional text to specific names. The current implementation opens files sequentially, which may not be optimal.

Solution:

Python allows using multiple open() statements within a single with statement by comma-separating them. This enables handling multiple files simultaneously and enhances resource management.

def filter(txt, oldfile, newfile):
    '''
    Read a list of names from a file line by line into an output file.
    If a line begins with a particular name, insert a string of text
    after the name before appending the line to the output file.
    '''

    with open(newfile, 'w') as outfile, open(oldfile, 'r', encoding='utf-8') as infile:
        for line in infile:
            if line.startswith(txt):
                line = line[0:len(txt)]   ' - Truly a great person!\n'
            outfile.write(line)

Additional Notes:

• Explicitly returning from a function with no return value is unnecessary.
• This feature was introduced in Python 2.7 and 3.1 or newer.
• If compatibility with Python versions 2.5 or 2.6 is required, nesting with statements or using contextlib.nested is recommended.

By optimizing file handling in this manner, developers can enhance code readability, resource management, and overall efficiency.