Python Function to Extract Command and Comment from a Line in a Script

python: extract command and comment from a line in a text script

To extract a command and its associated comment from a line in a text script using Python, you can use regular expressions or simple string operations. Here’s a straightforward approach using string operations:

1. Split the line into the command and the comment based on the presence of a comment character (e.g., # for Python scripts).
2. Trim any leading or trailing whitespace from the command and comment.

Here is a sample Python function to achieve this:

def extract_command_and_comment(line, comment_char='#'):
    """
    Extracts the command and comment from a line of text.

    Parameters:
    line (str): The line of text to process.
    comment_char (str): The character that denotes the start of a comment.

    Returns:
    tuple: A tuple containing the command and the comment.
    """
    # Split the line at the first occurrence of the comment character
    parts = line.split(comment_char, 1)
    
    # Extract the command and comment, trimming any extra whitespace
    command = parts[0].strip()
    comment = parts[1].strip() if len(parts) > 1 else ''
    
    return command, comment

# Example usage
line = "print('Hello, world!')  # This prints a greeting"
command, comment = extract_command_and_comment(line)
print(f"Command: '{command}'")
print(f"Comment: '{comment}'")

Explanation:

1. Splitting the Line: The split method is used to divide the line into two parts at the first occurrence of the comment character (#). The 1 argument ensures that the split happens only once, resulting in at most two parts.
2. Trimming Whitespace: The strip method is used to remove any leading or trailing whitespace from both the command and the comment.
3. Handling Absence of Comment: If there is no comment character in the line, the split method will return a list with a single element. The ternary operator (if len(parts) > 1 else '') ensures that the comment is an empty string in such cases.

This function can be easily adapted to handle different comment characters by changing the `