Python Decimal 类型不是 Real？

Question

这个问题已经有答案了:

Why is not 'decimal.Decimal(1)' an instance of 'numbers.Real'? (1 个回答)

已关闭 4 年前。

考虑以下因素:

from decimal import Decimal
from numbers import Number, Complex, Real

z = Decimal(0)

# Expected: a == b == c == True
# Actual (Python 3.6.5):
a = isinstance(z, Number)  # True
b = isinstance(z, Complex) # False
c = isinstance(z, Real)    # False

Decimal似乎实现了需要考虑的一切Real根据PEP3141 ，那么什么给出呢？值得注意的是，fractions.Fraction已按上述代码片段正确分类(例如 a == b == c == True )。

Answer 1

这实际上在PEP 3141中提到过:

After consultation with its authors it has been decided that the Decimal type should not at this time be made part of the numeric tower.

因此故意排除了十进制。