from structure import Structure
from validate import PositiveFloat, PositiveInteger, String


class Stock(Structure):
    _types = ()
    name = String()
    shares = PositiveInteger()
    price = PositiveFloat()

    @property
    def cost(self):
        return self.shares * self.price

    def sell(self, nshares: PositiveInteger):
        self.shares -= nshares

    @classmethod
    def from_row(cls, row):
        rowdata = [func(val) for func, val in zip(cls._types, row)]
        return cls(*rowdata)