type/rate.py

   1 #!/usr/bin/env python3
   2
   3 from typing import Optional
   4
   5
   6 class Rate(object):
   7     def __init__(
   8             self,
   9             multiplier: Optional[float] = None,
  10             *,
  11             percentage: Optional[float] = None,
  12             percent_change: Optional[float] = None,
  13     ):
  14         count = 0
  15         if multiplier is not None:
  16             if isinstance(multiplier, str):
  17                 multiplier = multiplier.replace('%', '')
  18                 m = float(multiplier)
  19                 m /= 100
  20                 self.multiplier = m
  21             else:
  22                 self.multiplier = multiplier
  23             count += 1
  24         if percentage is not None:
  25             self.multiplier = percentage / 100
  26             count += 1
  27         if percent_change is not None:
  28             self.multiplier = 1.0 + percent_change / 100
  29             count += 1
  30         if count != 1:
  31             raise Exception(
  32                 'Exactly one of percentage, percent_change or multiplier is required.'
  33             )
  34
  35     def apply_to(self, other):
  36         return self.__mul__(other)
  37
  38     def of(self, other):
  39         return self.__mul__(other)
  40
  41     def __float__(self):
  42         return self.multiplier
  43
  44     def __mul__(self, other):
  45         return self.multiplier * float(other)
  46
  47     __rmul__ = __mul__
  48
  49     def __truediv__(self, other):
  50         return self.multiplier / float(other)
  51
  52     def __add__(self, other):
  53         return self.multiplier + float(other)
  54
  55     __radd__ = __add__
  56
  57     def __sub__(self, other):
  58         return self.multiplier - float(other)
  59
  60     def __eq__(self, other):
  61         return self.multiplier == float(other)
  62
  63     def __ne__(self, other):
  64         return not self.__eq__(other)
  65
  66     def __lt__(self, other):
  67         return self.multiplier < float(other)
  68
  69     def __gt__(self, other):
  70         return self.multiplier > float(other)
  71
  72     def __le__(self, other):
  73         return self < other or self == other
  74
  75     def __ge__(self, other):
  76         return self > other or self == other
  77
  78     def __hash__(self):
  79         return self.multiplier
  80
  81     def __repr__(self,
  82                  *,
  83                  relative=False,
  84                  places=3):
  85         if relative:
  86             percentage = (self.multiplier - 1.0) * 100.0
  87         else:
  88             percentage = self.multiplier * 100.0
  89         return f'{percentage:+.{places}f}%'