110 lines
2.5 KiB
Python
110 lines
2.5 KiB
Python
class Validator:
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def __init__(self, name=None):
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self.name = name
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def __set_name__(self, cls, name):
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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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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('must be >= 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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raise 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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from inspect import signature
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class ValidatedFunction:
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def __init__(self, func):
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self.func = func
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self.signature = signature(func)
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self.annotations = dict(func.__annotations__)
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self.retcheck = self.annotations.pop('return', None)
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def __call__(self, *args, **kwargs):
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bound = self.signature.bind(*args, **kwargs)
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for name, val in self.annotations.items():
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val.check(bound.arguments[name])
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result = self.func(*args, **kwargs)
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if self.retcheck:
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self.retcheck.check(result)
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return result
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# Examples
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if __name__ == '__main__':
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def add(x:Integer, y:Integer) -> Integer:
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return x + y
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add = ValidatedFunction(add)
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class Stock:
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name = NonEmptyString()
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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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@property
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def cost(self):
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return self.shares * self.price
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def sell(self, nshares):
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self.shares -= nshares
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sell = ValidatedFunction(sell) # Broken
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