diff.py 文件源码

def diff(filename1, filename2):
    if not os.path.exists(filename1):
        msg = NOT_EXISTS.format(filename1)
        print(msg, file=sys.stderr)
        sys.exit(1)

    if not os.path.exists(filename2):
        msg = NOT_EXISTS.format(filename2)
        print(msg, file=sys.stderr)
        sys.exit(1)

    with open(filename1, 'r') as file_obj:
        lines1 = file_obj.readlines()

    with open(filename2, 'r') as file_obj:
        lines2 = file_obj.readlines()

    if lines1 == lines2:
        msg = '{} and {} are identical'.format(filename1, filename2)
        print(msg)
    else:
        diff_lines = difflib.context_diff(
            lines1, lines2, fromfile=filename1, tofile=filename2)
        print(''.join(diff_lines))
        sys.exit(1)