Implement full numerical methods on the Sides API

ppb/sprites.py

@@ -4,6 +4,7 @@
 
 from ppb import Vector
 from ppb.events import EventMixin
+from ppb.utils import FauxFloat
 
 import ppb_vector.vector2
 
@@ -17,7 +18,7 @@
 side_attribute_error_message = error_message.format
 
 
-class Side:
+class Side(FauxFloat):
     sides = {
         LEFT: ('x', -1),
         RIGHT: ('x', 1),
@@ -33,51 +34,20 @@ def __repr__(self):
         return f"Side({self.parent!r}, {self.side!r})"
 
     def __str__(self):
-        return str(self.value)
-
-    def __add__(self, other):
-        return self.value + other
-
-    def __radd__(self, other):
-        return other + self.value
-
-    def __sub__(self, other):
-        return self.value - other
-
-    def __rsub__(self, other):
-        return other - self.value
-
-    def __eq__(self, other):
-        return self.value == other
-
-    def __le__(self, other):
-        return self.value <= other
-
-    def __ge__(self, other):
-        return self.value >= other
-
-    def __ne__(self, other):
-        return self.value != other
-
-    def __gt__(self, other):
-        return self.value > other
-
-    def __lt__(self, other):
-        return self.value < other
+        return str(float(self))
 
     def _lookup_side(self, side):
         dimension, sign = self.sides[side]
         return dimension, sign * self.parent._offset_value
 
-    @property
-    def value(self):
+    def __float__(self):
         dimension, offset = self._lookup_side(self.side)
         return self.parent.position[dimension] + offset
 
     @property
     def top(self):
         self._attribute_gate(TOP, [TOP, BOTTOM])
-        return Vector(self.value, self.parent.top.value)
+        return Vector(float(self), float(self.parent.top))
 
     @top.setter
     def top(self, value):
@@ -87,7 +57,7 @@ def top(self, value):
     @property
     def bottom(self):
         self._attribute_gate(BOTTOM, [TOP, BOTTOM])
-        return Vector(self.value, self.parent.bottom.value)
+        return Vector(float(self), float(self.parent.bottom))
 
     @bottom.setter
     def bottom(self, value):
@@ -97,7 +67,7 @@ def bottom(self, value):
     @property
     def left(self):
         self._attribute_gate(LEFT, [LEFT, RIGHT])
-        return Vector(self.parent.left.value, self.value)
+        return Vector(float(self.parent.left), float(self))
 
     @left.setter
     def left(self, value):
@@ -107,7 +77,7 @@ def left(self, value):
     @property
     def right(self):
         self._attribute_gate(RIGHT, [LEFT, RIGHT])
-        return Vector(self.parent.right.value, self.value)
+        return Vector(float(self.parent.right), float(self))
 
     @right.setter
     def right(self, value):
@@ -117,9 +87,9 @@ def right(self, value):
     @property
     def center(self):
         if self.side in (TOP, BOTTOM):
-            return Vector(self.parent.center.x, self.value)
+            return Vector(self.parent.center.x, float(self))
         else:
-            return Vector(self.value, self.parent.center.y)
+            return Vector(float(self), self.parent.center.y)
 
     @center.setter
     def center(self, value):

ppb/utils.py

@@ -1,7 +1,9 @@
 import logging
 import sys
+import numbers
+import math
 
-__all__ = 'LoggingMixin',
+__all__ = 'LoggingMixin', 'FauxFloat',
 
 
 # Dictionary mapping file names -> module names
@@ -48,3 +50,88 @@ def logger(self):
 
         module_name = _get_module(file_name)
         return logging.getLogger(module_name)
+
+
+class FauxFloat(numbers.Real):
+    """
+    When applied to a class that implements __float__, provides the full suite
+    of number-related special methods.
+
+    While this mixin doesn't do anything about it, you should consider makiing
+    your class immutable. Odd things could potentially happen otherwise.
+    """
+
+    def __abs__(self):
+        return float(self).__abs__()
+
+    def __add__(self, other):
+        return float(self).__add__(other)
+
+    def __ceil__(self):
+        return math.ceil(float(self))
+
+    def __eq__(self, other):
+        return float(self).__eq__(other)
+
+    def __float__(self, other):
+        return float(self).__float__(other)
+
+    def __floor__(self):
+        return math.floor(float(self))
+
+    def __floordiv__(self, other):
+        return float(self).__floordiv__(other)
+
+    def __ge__(self, other):
+        return float(self).__ge__(other)
+
+    def __gt__(self, other):
+        return float(self).__gt__(other)
+
+    def __le__(self, other):
+        return float(self).__le__(other)
+
+    def __lt__(self, other):
+        return float(self).__lt__(other)
+
+    def __mod__(self, other):
+        return float(self).__mod__(other)
+
+    def __mul__(self, other):
+        return float(self).__mul__(other)
+
+    def __neg__(self):
+        return float(self).__neg__()
+
+    def __pos__(self):
+        return float(self).__pos__()
+
+    def __pow__(self, other):
+        return float(self).__pow__(other)
+
+    def __radd__(self, other):
+        return float(self).__radd__(other)
+
+    def __rfloordiv__(self, other):
+        return float(self).__rfloordiv__(other)
+
+    def __rmod__(self, other):
+        return float(self).__rmod__(other)
+
+    def __rmul__(self, other):
+        return float(self).__rmul__(other)
+
+    def __round__(self, ndigits=None):
+        return float(self).__round__(ndigits)
+
+    def __rpow__(self, other):
+        return float(self).__rpow__(other)
+
+    def __rtruediv__(self, other):
+        return float(self).__rtruediv__(other)
+
+    def __truediv__(self, other):
+        return float(self).__truediv__(other)
+
+    def __trunc__(self):
+        return float(self).__trunc__()

requirements-tests.txt

@@ -1 +1,2 @@
 pytest
+hypothesis

tests/test_fauxfloat.py

@@ -0,0 +1,90 @@
+import math
+import operator
+
+from ppb.utils import FauxFloat
+
+import pytest
+
+from hypothesis import given, assume
+import hypothesis.strategies as st
+
+
+def get_thingy(num):
+    class Thingy(FauxFloat):
+        def __float__(self):
+            return num
+
+    return Thingy()
+
+
+# The use of parametrize() over st.sampled_from() is deliberate.
+
+
+@pytest.mark.parametrize(
+    "operation",
+    [
+        float, abs, bool, int, math.ceil, math.floor, math.trunc, operator.neg,
+        operator.pos,
+    ],
+)
+@given(num=st.floats(allow_nan=False, allow_infinity=False))
+def test_unary_ops(operation, num):
+    t = get_thingy(num)
+
+    assert operation(t) == operation(num)
+
+
+@pytest.mark.parametrize(
+    "operation",
+    [
+        operator.lt, operator.le, operator.eq, operator.ne, operator.ge,
+        operator.gt, operator.add, operator.mul, operator.sub,
+    ],
+)
+@given(
+    num=st.floats(allow_nan=False, allow_infinity=False),
+    other=st.floats(allow_nan=False, allow_infinity=False),
+)
+def test_binary_ops(operation, num, other):
+    t = get_thingy(num)
+
+    assert operation(t, other) == operation(num, other)
+    assert operation(other, t) == operation(other, num)
+
+
+@pytest.mark.parametrize(
+    "operation",
+    [
+        operator.floordiv, operator.mod, operator.truediv,
+    ],
+)
+@given(
+    num=st.floats(allow_nan=False, allow_infinity=False),
+    other=st.floats(allow_nan=False, allow_infinity=False),
+)
+def test_binary_ops_nonzero(operation, num, other):
+    assume(num != 0)
+    assume(other != 0)
+    t = get_thingy(num)
+
+    assert operation(t, other) == operation(num, other)
+    assert operation(other, t) == operation(other, num)
+
+
+@given(
+    base=st.floats(allow_nan=False, allow_infinity=False, min_value=-1e20, max_value=1e20),
+    exponent=st.floats(allow_nan=False, allow_infinity=False, min_value=-10, max_value=10),
+)
+def test_pow(base, exponent):
+    assume(base != 0 and exponent != 0)
+
+    assert operator.pow(get_thingy(base), exponent) == operator.pow(base, exponent)
+    assert operator.pow(base, get_thingy(exponent)) == operator.pow(base, exponent)
+
+
+@given(
+    num=st.floats(allow_nan=False, allow_infinity=False),
+    digits=st.integers() | st.none(),
+)
+def test_round(num, digits):
+    assert round(get_thingy(num), digits) == round(num, digits)