100 lines
2.0 KiB
Python
100 lines
2.0 KiB
Python
class Validator:
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def __init__(self, name=None):
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self.name = name
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@classmethod
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def check(cls, value):
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return value
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def __set__(self, instance, value):
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instance.__dict__[self.name] = self.check(value)
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def __set_name__(self, cls, name):
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self.name = name
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class Typed(Validator):
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expected_type = object
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@classmethod
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def check(cls, value):
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if not isinstance(value, cls.expected_type):
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raise TypeError(f"expected {cls.expected_type}")
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return super().check(value)
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class Integer(Typed):
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expected_type = int
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class Float(Typed):
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expected_type = float
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class String(Typed):
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expected_type = str
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class Positive(Validator):
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@classmethod
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def check(cls, value):
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if value < 0:
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raise ValueError("Expected >= 0")
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return super().check(value)
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class NonEmpty(Validator):
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@classmethod
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def check(cls, value):
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if len(value) == 0:
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return ValueError("Must be non-empty")
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return super().check(value)
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class PositiveInteger(Integer, Positive):
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pass
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class PositiveFloat(Float, Positive):
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pass
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class NonEmptyString(String, NonEmpty):
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pass
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class Stock:
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name = String()
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shares = PositiveInteger()
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price = PositiveFloat()
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def __init__(self, name, shares, price):
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self.name = name
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self.shares = shares
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self.price = price
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def __repr__(self):
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return f"Stock({self.name!r}, {self.shares!r}, {self.price!r})"
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def __eq__(self, other):
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if not isinstance(other, Stock):
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return False
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return (self.name, self.shares, self.price) == (
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other.name,
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other.shares,
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other.price,
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)
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@classmethod
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def from_row(cls, row):
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return cls(*row)
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@property
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def cost(self):
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return self.shares * self.price
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def sell(self, num):
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self.shares -= num
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if self.shares < 0:
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self.shares = 0
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