126 lines
4.0 KiB
Python
126 lines
4.0 KiB
Python
"""Dictionary of supported currencies as instances of a Currency class.
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Face values are stored as decimals*.
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* Decimal is used to avoid problems of rounding float numbers. So first two
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digits to the right are used to store a fraction part. You can simply divide
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this number by 100 to get a floating-point number.
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"""
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from __future__ import annotations
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from operator import mul
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from typing import Dict, List, TypedDict
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__all__ = [ "Currency", "CURRENCIES", "BaseCurrencyError",
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"CurrencyIsNotSupportedError", "CurrenciesCoinCountMismatchError",
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"CurrencyMismatchError"]
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CURRENCIES: Dict[str, Currency] = dict()
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class BaseCurrencyError(Exception):
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"""Base class for all currency exeptions."""
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def __init__(self, message=None, *args, **kwargs) -> None:
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if message is None:
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message = self.__doc__
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super().__init__(message, *args, **kwargs)
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class CurrencyIsNotSupportedError(BaseCurrencyError):
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"""Currency is not supported."""
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pass
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class CurrencyMismatchError(BaseCurrencyError):
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"""Currencies doesn't match, but they must do so."""
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def __init__(self, extra=None):
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if not extra is None:
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super().__init__(f"{self.__doc__} {extra}")
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else:
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super().__init__(self.__doc__)
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class CurrenciesCoinCountMismatchError(BaseCurrencyError):
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"""Count of coins of a new currency and an old one should be equal."""
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pass
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class Currency:
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"""Currency's representation and methods to work with it.
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Arguments:
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iso_code -- ISO code of a currency;
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name -- full name of a currency;
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description -- description of a currency;
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coins_count -- number of face values of coins;
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coin_names -- list of names of face values (e.g. 1c, 5c);
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face_values -- list of values for each face value in decimal
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(e.g. $476.40 is 47640);
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"""
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def __init__(self, iso_code: str, name: str, description: str,
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coins_count: int, coin_names: List[str],
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face_values: List[int]):
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self._iso = iso_code.upper()
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self._name = name
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self._description = description
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self._coins_count = coins_count
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self._coin_names = coin_names
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self._face_values = face_values
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@property
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def iso(self) -> str:
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"""ISO code of a currency."""
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return self._iso
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@property
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def name(self) -> str:
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"""Full name of a currency."""
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return self._name
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@property
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def description(self) -> str:
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"""Description of a currency (e.g. country)."""
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return self._description
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@property
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def count(self):
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"""Count of coins of a currency."""
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return self._coins_count
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@property
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def coin_names(self) -> List[str]:
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"""Names of coins (usually face values, e.g. 25¢).
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From least to most."""
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return self._coin_names
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@property
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def face_values(self) -> List[int]:
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"""Face values of coins. From least to most."""
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return self._face_values
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def multiply(self, lst: List[int]) -> List[float]:
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"""Multiplies a list by face values. Length of list must match
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currency's coins count."""
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if len(lst) != len(self):
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raise CurrenciesCoinCountMismatchError
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return list(map(mul, lst, self.face_values))
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@staticmethod
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def from_string(currency: str) -> Currency:
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"""Creates a Currency object from its string representation."""
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iso, name, desc, ccnt, fvn, fv = currency.split(";")
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return Currency(iso, name, desc, int(ccnt),
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fvn.split(","), list(map(int, fv.split(","))))
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def __mul__(self, lst: List[int]) -> List[float]:
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return self.multiply(lst)
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def __len__(self) -> int:
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return self.count
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def __str__(self):
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return f"{self.iso};{self.name};{self.description};" \
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f"{self.count};{','.join(self.coin_names)};" \
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f"{','.join(list(map(str, self.face_values)))}"
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