Question

Python: How would I modify the class below that takes a string and returns an object holding a valid NANP phone number. I am asked to filll in the three methods listed, but underfined, below: __str__(), area_code(), and normalize(). My task is to clean up differently formatted telephone numbers by removing punctuation, such as '(', '-', and the like, and removing and the country code (1) if present. I am asked to start by stripping non-digits, and then see if the digits match the pattern. If asked to create a phone number that does not meet the pattern above, I should throw a ValueError with a string explaining the problem: too many or too few digits, or the wrong digits.

For example, the strings below

+1 (617) 495-4024

617-495-4024

1 617 495 4024

617.495.4024

should all produce an object that is printed as (617) 495-4024

ValueErrors

Each of the following strings should produce a ValueError exception.

+1 (617) 495-40247 has too many digits

(617) 495-402 has too few digits

+2 (617) 495-4024 has the wrong country code

(017) 495-4024 has an illegal area code

(617) 195-4024 has an illegal exchange code

class Phone:
"A Class defining valid Phone Numbers"
  
def __init__(self, raw):
"Create new instance"
self.number = self._normalize(raw)

def __str__(self) -> str:
"Create printable representation"
pass

def area_code(self) -> str:
"Return the area code"
pass

def _normalize(self, raw: str) -> str:
""""Take string presented and return string with digits
Throws a ValueError Exception if not a NANP number"""
pass

Answer 1

class Phone:

    "A Class defining valid Phone Numbers"

    def __init__(self, raw):

        "Create new instance"

        self.number = self._normalize(raw)

    def __str__(self) -> str:

        "Create printable representation"

        # remove area code

        if self.number[0] == '1':

            return f'({self.number[1:4]}) {self.number[4:7]}-{self.number[7:]}'

        return f'({self.number[0:3]}) {self.number[3:6]}-{self.number[6:]}'

        pass

    def area_code(self) -> str:

        return str(self.number[0]) + str(self.number[1]) + str(self.number[2])

    def _normalize(self, raw: str) -> str:

        """"Take string presented and return string with digits

        Throws a ValueError Exception if not a NANP number"""

        # string to return

        number = ""

        for digit in raw:

            if digit.isdigit():

                number += digit

        if number[0] == '1':

            if len(number) > 11:

                raise ValueError(raw)

        elif len(number) > 10:

            raise ValueError(raw)

        return number

# testing

# For example, the strings below

try:

    print(Phone("+1 (617) 495-4024"))

    print(Phone("617-495-4024"))

    print(Phone("1 617 495 4024"))

    print(Phone("617.495.4024"))

    # should all produce an object that is printed as (617) 495-4024

    # following string should produce a ValueError exception.

    print(Phone("+1 (617) 495-40247"))

except ValueError as raw:

    print("error in ", raw)

    pass

.

Screenshot:

Output:

.