How can I save a file with the name as: oldname+"_new"+extension in an elegant way?

I currently do:

ext = os.path.splitext(file)[1]
output_file = (root+'/'+ os.path.splitext(file)[0]+"_new"+ext)
#or output_file = (os.path.join(root, os.path.splitext(file)[0])+'_new'+ext)with open(output_file, 'w', encoding='utf-8') as file:file.write(text)

(with the help of Python: how to retain the file extension when renaming files with os? , but not duplicate)

-- I use Python 3.12.2

pathlib.Path is preferred in modern code for a more OO approach.

For example:

from pathlib import Pathdef makenew(filename: Path, new: str = "_new") -> Path:return filename.parent / (filename.stem + new + filename.suffix)print(makenew(Path("/Users/SIGHUP/foo.txt")))

Output:

/Users/SIGHUP/foo_new.txt