gh-121797: Add class method Fraction.from_number() #121800
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It is an alternative constructor which only accepts a single numeric argument. Unlike to Fraction.from_float() and Fraction.from_decimal() it accepts any real numbers supported by the standard constructor (int, float, Decimal, Rational numbers). Unlike to the standard constructor, it does not accept strings.
| @@ -305,6 +306,28 @@ def __new__(cls, numerator=0, denominator=None): | |||
| self._denominator = denominator | |||
| return self | |||
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| @classmethod | |||
| def from_number(cls, number): | |||
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Hmm, you can reuse this in the RationalFraction constructor, isn't? First three if/elif's share exactly same logic.
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Do you mean the main Fraction constructor?
There is a different exception if the argument type is not supported. There is also a matter of performance.
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I meant some helper:
@classmethod
def _from_number(cls, number):
if type(number) is int:
return cls._from_coprime_ints(number, 1)
elif isinstance(number, numbers.Rational):
return cls._from_coprime_ints(number.numerator, number.denominator)
elif (isinstance(number, float) or
(not isinstance(number, type) and
hasattr(number, 'as_integer_ratio'))):
return cls._from_coprime_ints(*number.as_integer_ratio())Then you can reuse one in the constructor and in the from_number(), e.g.:
if denominator is None:
self = cls._from_number(numerator)
if self is not None:
return self
elif isinstance(numerator, str):
...
There is also a matter of performance.
I don't expect too much from extra class method call.
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Extra function call and extra check.
This will not save much code. I'll leave this on future if we touch this code again.
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Well, it's up to you. PR has Mark approval, so it's ready to go.
It is an alternative constructor which only accepts a single numeric argument. Unlike to Fraction.from_float() and Fraction.from_decimal() it accepts any real numbers supported by the standard constructor (int, float, Decimal, Rational numbers).
Unlike to the standard constructor, it does not accept strings.
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