cast from & to decimal (#26)

lib/fixedpointmath/fixedpointmath/fixed_point.py

@@ -2,12 +2,13 @@
 from __future__ import annotations
 
 import re
+from decimal import Decimal
 from typing import Any, Literal, Union, get_args
 
 from . import errors
 from .fixed_point_integer_math import FixedPointIntegerMath
 
-OtherTypes = Union[int, bool, float]
+OtherTypes = Union[int, bool, float, Decimal]
 SpecialValues = Literal["nan", "inf", "-inf"]
 
 
@@ -31,6 +32,7 @@ class FixedPoint:
     _scaled_value: int  # integer representation of self
     _special_value: SpecialValues | None  # string representation of self
 
+    # pylint: disable=too-many-branches
     def __init__(
         self,
         unscaled_value: OtherTypes | str | FixedPoint | None = None,  # use default conversion
@@ -70,6 +72,8 @@ def __init__(
                 self._set_int(unscaled_value)
             elif isinstance(unscaled_value, str):
                 self._set_str(unscaled_value)
+            elif isinstance(unscaled_value, Decimal):
+                self._set_str(str(unscaled_value))
             elif isinstance(unscaled_value, FixedPoint):
                 self._set_fixedpoint(unscaled_value)
             else:
@@ -116,13 +120,10 @@ def _set_str(self, unscaled_value: str) -> None:
                 exponent = int(exp_split[1])
             else:
                 exponent = 0
-
             if "." not in mantissa:  # input is always assumed to be a float
                 mantissa += ".0"
-
             # removes underscores; they won't affect `int` cast and will affect `len`
             mantissa = mantissa.replace("_", "")
-
             integer, remainder = mantissa.split(".")
             is_negative = "-" in integer
             if is_negative:
@@ -228,12 +229,18 @@ def _coerce_other(self, other: OtherTypes | FixedPoint) -> FixedPoint:
             return other
         if isinstance(other, int):
             return FixedPoint(other)
+        if isinstance(other, Decimal):
+            return FixedPoint(other)
         if isinstance(other, float):  # currently don't allow (most) floats
             if other == 0.0:  # 0 is unambiguous, so we will allow it
                 return FixedPoint(other)
             raise TypeError(f"unsupported operand type(s): {type(other)}")
         raise TypeError(f"unsupported operand type(s): {type(other)}")
 
+    def to_decimal(self) -> Decimal:
+        r"""Convert self to a Decimal type"""
+        return Decimal(str(self))
+
     def __add__(self, other: OtherTypes | FixedPoint) -> FixedPoint:
         r"""Enables '+' syntax"""
         other = self._coerce_other(other)

lib/fixedpointmath/pyproject.toml

@@ -1,6 +1,6 @@
 [project]
 name = "fixedpointmath"
-version = "0.1.3"
+version = "0.1.4"
 authors = [
     { name = "Dylan Paiton", email = "dylan@delv.tech" },
     { name = "Mihai Cosma", email = "mihai@delv.tech" },

lib/fixedpointmath/tests/test_fp_class.py

@@ -1,9 +1,9 @@
 """Tests for the FixedPoint class methods"""
 import math
 import unittest
+from decimal import Decimal
 
-from fixedpointmath import errors
-from fixedpointmath import FixedPoint
+from fixedpointmath import FixedPoint, errors
 
 
 class TestFixedPoint(unittest.TestCase):
@@ -41,6 +41,8 @@ def test_init(self):
         assert int(FixedPoint(5)) == 5  # int input directly maps, cast does not rescale
         assert float(FixedPoint(5.0)) == 5.0  # scales up on init, then back down on cast to float
         assert int(FixedPoint(5)) == float(FixedPoint(5.0))
+        # decimal == float
+        assert FixedPoint(Decimal("5.0")) == FixedPoint(5.0)
         # bool
         assert FixedPoint(True) == FixedPoint(1.0)
         assert FixedPoint(False) == FixedPoint(0.0)
@@ -130,8 +132,16 @@ def test_str_cast(self):
         assert str(FixedPoint(True)) == "1.0"
         assert str(FixedPoint(False)) == "0.0"
 
+    def test_decimal_cast(self):
+        r"""Test Decimal casting"""
+        assert FixedPoint("0.15").to_decimal() == Decimal("0.15")
+        assert float(FixedPoint("0.15").to_decimal()) == 0.15
+        assert FixedPoint(Decimal("0.15")) == FixedPoint("0.15")
+        assert int(FixedPoint(Decimal(5))) == 5
+        assert isinstance(FixedPoint(5.52).to_decimal(), Decimal)
+
     def test_repr(self):
-        """Test the repr method"""
+        r"""Test the repr method"""
         # pylint: disable=unnecessary-dunder-call
         assert self.INF.__repr__() == 'FixedPoint("inf")'
         assert self.NEG_INF.__repr__() == 'FixedPoint("-inf")'