Validate PPSN (Ireland)

ppsn.py

import logging
logging.basicConfig(level=logging.INFO)


def calculate_check(text):
    total = 0
    for i in range(0,7):
        total += int(text[i]) * (8-i)
    if len(text) == 9:
        total += ("ABCDEFGHIJKLMNOPQRSTU".find(text[8])+1)*9
    remainder = total % 23
    character = "ABCDEFGHIJKLMNOPQRSTUV"[remainder-1]
    logging.info(character)
    return character


def valid_ppsn(text):

    text = text.upper()

# test for string length 8 or 9

    if len(text) != 8 and len(text) != 9:
        logging.info("Fails length test.")
        return False

# test characters 1 to 7 are digits

    if not text[:7].isdigit():
        logging.info("Fails the digit test.")
        return False

# test character 8 is a letter in A to V

    if text[7] not in "ABCDEFGHIJKLMNOPQRSTUV":
        logging.info("Fails the first letter test.")
        return False

# test character 9 (if exists) is in W, H, A

    if len(text) == 9:
        if text[8] not in "AHW":
            logging.info("Fails the second letter test.")
            return False

# test checksum

    if text[7] != calculate_check(text):
        logging.info("Fails checksum.")
        return False

    logging.info("Passes all tests.")

    return True

Validate PPS number format, not validate PPS. Its misleading I feel

Validate PPS number format, not validate PPS. Its misleading I feel

Validation is the process of checking something against specifications. In this case the specifications of PPSN format. What is a usecase for validate PPSN (which is a code format) that isn't validating the number format?

"Validate PPS number" means "check that this is a valid PPS number", not "check that this PPS number has been assigned". I think most people would expect the former, not the latter, so I don't think this is misleading. Same thing applies for IBAN number checkers etc -- they don't connect to every bank worldwide to check if the number is associated with an actual bank account (consider the privacy implications of that).