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PiggyBank/piggybank/currencies.py

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"""Dictionary of supported currencies as instances of a Currency class.
Face values are stored as decimals*.
* Decimal is used to avoid problems of rounding float numbers. So first two
digits to the right are used to store a fraction part. You can simply divide
this number by 100 to get a floating-point number.
"""
from __future__ import annotations
from operator import mul
from typing import Dict, List, TypedDict
__all__ = [ "Currency", "CURRENCIES", "BaseCurrencyError",
"CurrencyIsNotSupportedError", "CurrenciesCoinCountMismatchError",
"CurrencyMismatchError"]
CURRENCIES: Dict[str, Currency] = dict()
class BaseCurrencyError(Exception):
"""Base class for all currency exeptions."""
def __init__(self, message=None, *args, **kwargs) -> None:
if message is None:
message = self.__doc__
super().__init__(message, *args, **kwargs)
class CurrencyIsNotSupportedError(BaseCurrencyError):
"""Currency is not supported."""
pass
class CurrencyMismatchError(BaseCurrencyError):
"""Currencies doesn't match, but they must do so."""
def __init__(self, extra=None):
if not extra is None:
super().__init__(f"{self.__doc__} {extra}")
else:
super().__init__(self.__doc__)
class CurrenciesCoinCountMismatchError(BaseCurrencyError):
"""Count of coins of a new currency and an old one should be equal."""
pass
class Currency:
"""Currency's representation and methods to work with it.
Arguments:
iso_code -- ISO code of a currency;
name -- full name of a currency;
description -- description of a currency;
coins_count -- number of face values of coins;
coin_names -- list of names of face values (e.g. 1c, 5c);
face_values -- list of values for each face value in decimal
(e.g. $476.40 is 47640);
"""
def __init__(self, iso_code: str, name: str, description: str,
coins_count: int, coin_names: List[str],
face_values: List[int]):
self._iso = iso_code.upper()
self._name = name
self._description = description
self._coins_count = coins_count
self._coin_names = coin_names
self._face_values = face_values
@property
def iso(self) -> str:
"""ISO code of a currency."""
return self._iso
@property
def name(self) -> str:
"""Full name of a currency."""
return self._name
@property
def description(self) -> str:
"""Description of a currency (e.g. country)."""
return self._description
@property
def count(self):
"""Count of coins of a currency."""
return self._coins_count
@property
def coin_names(self) -> List[str]:
"""Names of coins (usually face values, e.g. 25¢).
From least to most."""
return self._coin_names
@property
def face_values(self) -> List[int]:
"""Face values of coins. From least to most."""
return self._face_values
def multiply(self, lst: List[int]) -> List[float]:
"""Multiplies a list by face values. Length of list must match
currency's coins count."""
if len(lst) != len(self):
raise CurrenciesCoinCountMismatchError
return list(map(mul, lst, self.face_values))
@staticmethod
def from_string(currency: str) -> Currency:
"""Creates a Currency object from its string representation."""
iso, name, desc, ccnt, fvn, fv = currency.split(";")
return Currency(iso, name, desc, int(ccnt),
fvn.split(","), list(map(int, fv.split(","))))
def __mul__(self, lst: List[int]) -> List[float]:
return self.multiply(lst)
def __len__(self) -> int:
return self.count
def __str__(self):
return f"{self.iso};{self.name};{self.description};" \
f"{self.count};{','.join(self.coin_names)};" \
f"{','.join(list(map(str, self.face_values)))}"
# CURRENCIES: Dict[str, Currency] = {
# "RUB": Currency("RUB", "Russian ruble", "Russian Federation", 8,
# ["1к.", "5к.", "10к.", "50к.", "1₽", "2₽", "5₽", "10₽"],
# [1, 5, 10, 50, 1_00, 2_00, 5_00, 10_00]),
# "SRUB": Currency("SRUB", "Russian ruble (shortened)",
# "Russian Federation. Excluding coins of 1 and 5 kopek.",
# 6, ["10к.", "50к.", "1₽", "2₽", "5₽", "10₽"],
# [10, 50, 1_00, 2_00, 5_00, 10_00]),
# "BYN": Currency("BYN", "Belarusian ruble", "Belarus", 8,
# ["1к.", "2к.", "5к.", "10к.", "20к.", "50к.", "1р.", "2р."],
# [1, 2, 5, 10, 20, 50, 1_00, 2_00]),
# "UAH": Currency("UAH", "Ukrainian hryvnia", "Ukraine", 10,
# ["1к.", "2к.", "5к.", "10к.", "25к.", "50к.", "₴1", "₴2", "₴5", "₴10"],
# [1, 2, 5, 10, 25, 50, 1_00, 2_00, 5_00, 10_00]),
# "USD": Currency("USD", "US Dollar", "United States of America", 6,
# ["1¢", "5¢", "10¢", "25¢", "50¢", "$1"],
# [1, 5, 10, 25, 50, 1_00]),
# "EUR": Currency("EUR", "Euro", "European Union", 8,
# ["1c", "2c", "5c", "10c", "20c", "50c", "€1", "€2"],
# [1, 2, 5, 10, 20, 50, 1_00, 2_00]),
# "GBP": Currency("GBP", "Pound sterling", "United Kingdom", 9,
# ["1p", "2p", "5p", "10p", "20p", "25p", "50p", "£1", "£2"],
# [1, 2, 5, 10, 20, 25, 50, 1_00, 2_00])
# }