diff --git a/pyRCV2/numbers/base.py b/pyRCV2/numbers/base.py
new file mode 100644
index 0000000..4c01801
--- /dev/null
+++ b/pyRCV2/numbers/base.py
@@ -0,0 +1,242 @@
+#   pyRCV2: Preferential vote counting
+#   Copyright © 2020–2021  Lee Yingtong Li (RunasSudo)
+#
+#   This program is free software: you can redistribute it and/or modify
+#   it under the terms of the GNU Affero General Public License as published by
+#   the Free Software Foundation, either version 3 of the License, or
+#   (at your option) any later version.
+#
+#   This program is distributed in the hope that it will be useful,
+#   but WITHOUT ANY WARRANTY; without even the implied warranty of
+#   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+#   GNU Affero General Public License for more details.
+#
+#   You should have received a copy of the GNU Affero General Public License
+#   along with this program.  If not, see <https://www.gnu.org/licenses/>.
+
+__pragma__ = lambda x: None
+is_py = False
+__pragma__('skip')
+is_py = True
+import functools
+import math
+__pragma__('noskip')
+
+def compatible_types(f):
+	if is_py:
+		__pragma__('skip')
+		import os
+		if 'PYTEST_CURRENT_TEST' in os.environ:
+			@functools.wraps(f)
+			def wrapper(self, other):
+				if not isinstance(other, self.__class__):
+					raise ValueError('Attempt to operate on incompatible types')
+				return f(self, other)
+			return wrapper
+		else:
+			return f
+		__pragma__('noskip')
+	else:
+		# FIXME: Do we need to perform type checking in JS?
+		return f
+
+class BaseNum:
+	__slots__ = ['impl'] # Optimisation to reduce overhead of initialising new object
+	
+	# These enum values may be overridden in subclasses depending on underlying library
+	ROUND_DOWN = 0
+	ROUND_HALF_UP = 1
+	ROUND_HALF_EVEN = 2
+	ROUND_UP = 3
+	
+	def __init__(self, value):
+		if isinstance(value, self.__class__):
+			self.impl = value.impl
+		else:
+			self.impl = self._to_impl(value)
+	
+	@classmethod
+	def _to_impl(cls, value):
+		"""
+		Internal use: Convert the given value to an impl
+		Subclasses must override this method
+		"""
+		raise NotImplementedError('Method not implemented')
+	
+	@classmethod
+	def _from_impl(cls, impl):
+		"""Internal use: Return an instance directly from the given impl without performing checks"""
+		if is_py:
+			obj = cls.__new__(cls)
+		else:
+			# Transcrypt's __new__ (incorrectly) calls the constructor
+			obj = __pragma__('js', '{}', 'Object.create (cls, {__class__: {value: cls, enumerable: true}})')
+		obj.impl = impl
+		return obj
+	
+	def pp(self, dp):
+		"""
+		Pretty print to specified number of decimal places
+		Subclasses must override this method
+		"""
+		raise NotImplementedError('Method not implemented')
+	
+	# Implementation of arithmetic on impls
+	# Subclasses must override these functions:
+	
+	@classmethod
+	def _add_impl(cls, i1, i2):
+		raise NotImplementedError('Method not implemented')
+	@classmethod
+	def _sub_impl(cls, i1, i2):
+		raise NotImplementedError('Method not implemented')
+	@classmethod
+	def _mul_impl(cls, i1, i2):
+		raise NotImplementedError('Method not implemented')
+	@classmethod
+	def _truediv_impl(cls, i1, i2):
+		raise NotImplementedError('Method not implemented')
+	
+	@compatible_types
+	def __eq__(self, other):
+		raise NotImplementedError('Method not implemented')
+	@compatible_types
+	def __ne__(self, other):
+		return not (self.__eq__(other))
+	@compatible_types
+	def __gt__(self, other):
+		raise NotImplementedError('Method not implemented')
+	@compatible_types
+	def __ge__(self, other):
+		raise NotImplementedError('Method not implemented')
+	@compatible_types
+	def __lt__(self, other):
+		raise NotImplementedError('Method not implemented')
+	@compatible_types
+	def __le__(self, other):
+		raise NotImplementedError('Method not implemented')
+	
+	def round(self, dps, mode):
+		"""
+		Round to the specified number of decimal places, using the ROUND_* mode specified
+		Subclasses must override this method
+		"""
+		raise NotImplementedError('Method not implemented')
+	
+	# Implement various data model functions based on _*_impl
+	
+	@compatible_types
+	def __add__(self, other):
+		return self._from_impl(self._add_impl(self.impl, other.impl))
+	@compatible_types
+	def __sub__(self, other):
+		return self._from_impl(self._sub_impl(self.impl, other.impl))
+	@compatible_types
+	def __mul__(self, other):
+		return self._from_impl(self._mul_impl(self.impl, other.impl))
+	@compatible_types
+	def __truediv__(self, other):
+		return self._from_impl(self._truediv_impl(self.impl, other.impl))
+	
+	@compatible_types
+	def __iadd__(self, other):
+		self.impl = self._add_impl(self.impl, other.impl)
+		return self
+	@compatible_types
+	def __isub__(self, other):
+		self.impl = self._sub_impl(self.impl, other.impl)
+		return self
+	@compatible_types
+	def __imul__(self, other):
+		self.impl = self._mul_impl(self.impl, other.impl)
+		return self
+	@compatible_types
+	def __itruediv__(self, other):
+		self.impl = self._truediv_impl(self.impl, other.impl)
+		return self
+	
+	def __floor__(self):
+		return self.round(0, self.ROUND_DOWN)
+
+class BasePyNum(BaseNum):
+	"""Helper class for Num wrappers of Python objects that already implement overloading"""
+	
+	_py_class = None # Subclasses must specify
+	
+	@classmethod
+	def _to_impl(cls, value):
+		"""Implements BaseNum._to_impl"""
+		return cls._py_class(value)
+	
+	def pp(self, dp):
+		"""Implements BaseNum.pp"""
+		return format(self.impl, '.{}f'.format(dp))
+	
+	@classmethod
+	def _add_impl(cls, i1, i2):
+		"""Implements BaseNum._add_impl"""
+		return i1 + i2
+	@classmethod
+	def _sub_impl(cls, i1, i2):
+		"""Implements BaseNum._sub_impl"""
+		return i1 - i2
+	@classmethod
+	def _mul_impl(cls, i1, i2):
+		"""Implements BaseNum._mul_impl"""
+		return i1 * i2
+	@classmethod
+	def _truediv_impl(cls, i1, i2):
+		"""Implements BaseNum._truediv_impl"""
+		return i1 / i2
+	
+	@compatible_types
+	def __eq__(self, other):
+		"""Implements BaseNum.__eq__"""
+		return self.impl == other.impl
+	@compatible_types
+	def __ne__(self, other):
+		"""Overrides BaseNum.__ne__"""
+		return self.impl != other.impl
+	@compatible_types
+	def __gt__(self, other):
+		"""Implements BaseNum.__gt__"""
+		return self.impl > other.impl
+	@compatible_types
+	def __ge__(self, other):
+		"""Implements BaseNum.__ge__"""
+		return self.impl >= other.impl
+	@compatible_types
+	def __lt__(self, other):
+		"""Implements BaseNum.__lt__"""
+		return self.impl < other.impl
+	@compatible_types
+	def __le__(self, other):
+		"""Implements BaseNum.__le__"""
+		return self.impl <= other.impl
+	
+	@compatible_types
+	def __iadd__(self, other):
+		"""Overrides BaseNum.__iadd__"""
+		self.impl += other.impl
+		return self
+	@compatible_types
+	def __isub__(self, other):
+		"""Overrides BaseNum.__isub__"""
+		self.impl -= other.impl
+		return self
+	@compatible_types
+	def __imul__(self, other):
+		"""Overrides BaseNum.__imul__"""
+		self.impl *= other.impl
+		return self
+	@compatible_types
+	def __itruediv__(self, other):
+		"""Overrides BaseNum.__itruediv__"""
+		self.impl /= other.impl
+		return self
+	
+	def __floor__(self):
+		return self._from_impl(math.floor(self.impl))
+	
+	def __repr__(self):
+		return '<{} {}>'.format(self.__class__.__name__, str(self.impl))
diff --git a/pyRCV2/numbers/fixed_js.py b/pyRCV2/numbers/fixed_js.py
index 4384af4..c0a4ccf 100644
--- a/pyRCV2/numbers/fixed_js.py
+++ b/pyRCV2/numbers/fixed_js.py
@@ -1,5 +1,5 @@
 #   pyRCV2: Preferential vote counting
-#   Copyright © 2020  Lee Yingtong Li (RunasSudo)
+#   Copyright © 2020–2021  Lee Yingtong Li (RunasSudo)
 #
 #   This program is free software: you can redistribute it and/or modify
 #   it under the terms of the GNU Affero General Public License as published by
@@ -14,61 +14,65 @@
 #   You should have received a copy of the GNU Affero General Public License
 #   along with this program.  If not, see <https://www.gnu.org/licenses/>.
 
+from pyRCV2.numbers.base import BaseNum, compatible_types
+
 Big.DP = 6
 
 def set_dps(dps):
 	Big.DP = dps
 
-class Fixed:
+class Fixed(BaseNum):
 	"""
 	Wrapper for big.js (fixed-point arithmetic)
 	"""
 	
-	ROUND_DOWN = 0
-	ROUND_HALF_UP = 1
-	ROUND_HALF_EVEN = 2
-	ROUND_UP = 3
-	
-	def __init__(self, val):
-		if isinstance(val, Fixed):
-			self.impl = val.impl
-		else:
-			self.impl = Big(val).round(Big.DP)
+	@classmethod
+	def _to_impl(cls, value):
+		"""Implements BaseNum._to_impl"""
+		return Big(value).round(Big.DP)
 	
 	def pp(self, dp):
-		"""Pretty print to specified number of decimal places"""
+		"""Implements BaseNum.pp"""
 		return self.impl.toFixed(dp)
 	
-	def to_rational(self):
-		"""Convert to an instance of Rational"""
-		from pyRCV2.numbers import Rational
-		return Rational(self.impl.toString())
-	
-	def __add__(self, other):
-		return Fixed(self.impl.plus(other.impl))
-	def __sub__(self, other):
-		return Fixed(self.impl.minus(other.impl))
-	def __mul__(self, other):
-		return Fixed(self.impl.times(other.impl))
-	def __div__(self, other):
-		return Fixed(self.impl.div(other.impl))
+	@classmethod
+	def _add_impl(cls, i1, i2):
+		"""Implements BaseNum._add_impl"""
+		return i1.plus(i2)
+	@classmethod
+	def _sub_impl(cls, i1, i2):
+		"""Implements BaseNum._sub_impl"""
+		return i1.minus(i2)
+	@classmethod
+	def _mul_impl(cls, i1, i2):
+		"""Implements BaseNum._mul_impl"""
+		return i1.times(i2)
+	@classmethod
+	def _truediv_impl(cls, i1, i2):
+		"""Implements BaseNum._truediv_impl"""
+		return i1.div(i2)
 	
+	@compatible_types
 	def __eq__(self, other):
+		"""Implements BaseNum.__eq__"""
 		return self.impl.eq(other.impl)
-	def __ne__(self, other):
-		return not self.impl.eq(other.impl)
+	@compatible_types
 	def __gt__(self, other):
+		"""Implements BaseNum.__gt__"""
 		return self.impl.gt(other.impl)
+	@compatible_types
 	def __ge__(self, other):
+		"""Implements BaseNum.__ge__"""
 		return self.impl.gte(other.impl)
+	@compatible_types
 	def __lt__(self, other):
+		"""Implements BaseNum.__lt__"""
 		return self.impl.lt(other.impl)
+	@compatible_types
 	def __le__(self, other):
+		"""Implements BaseNum.__le__"""
 		return self.impl.lte(other.impl)
 	
-	def __floor__(self):
-		return self.round(0, Fixed.ROUND_DOWN)
-	
 	def round(self, dps, mode):
-		"""Round to the specified number of decimal places, using the ROUND_* mode specified"""
+		"""Implements BaseNum.round"""
 		return Fixed(self.impl.round(dps, mode))
diff --git a/pyRCV2/numbers/fixed_py.py b/pyRCV2/numbers/fixed_py.py
index 68fea8e..0a23efc 100644
--- a/pyRCV2/numbers/fixed_py.py
+++ b/pyRCV2/numbers/fixed_py.py
@@ -1,5 +1,5 @@
 #   pyRCV2: Preferential vote counting
-#   Copyright © 2020  Lee Yingtong Li (RunasSudo)
+#   Copyright © 2020–2021  Lee Yingtong Li (RunasSudo)
 #
 #   This program is free software: you can redistribute it and/or modify
 #   it under the terms of the GNU Affero General Public License as published by
@@ -14,9 +14,9 @@
 #   You should have received a copy of the GNU Affero General Public License
 #   along with this program.  If not, see <https://www.gnu.org/licenses/>.
 
+from pyRCV2.numbers.base import BasePyNum, compatible_types
+
 import decimal
-import functools
-import math
 
 _quantize_exp = 6
 
@@ -24,76 +24,23 @@ def set_dps(dps):
 	global _quantize_exp
 	_quantize_exp = decimal.Decimal('10') ** -dps
 
-def compatible_types(f):
-	@functools.wraps(f)
-	def wrapper(self, other):
-		if not isinstance(other, Fixed):
-			raise ValueError('Attempt to operate on incompatible types')
-		return f(self, other)
-	return wrapper
-
-class Fixed:
+class Fixed(BasePyNum):
 	"""
 	Wrapper for Python Decimal (for fixed-point arithmetic)
 	"""
 	
+	_py_class = decimal.Decimal # For BasePyNum
+	
 	ROUND_DOWN = decimal.ROUND_DOWN
 	ROUND_HALF_UP = decimal.ROUND_HALF_UP
 	ROUND_HALF_EVEN = decimal.ROUND_HALF_EVEN
 	ROUND_UP = decimal.ROUND_UP
 	
-	def __init__(self, val):
-		if isinstance(val, Fixed):
-			self.impl = val.impl
-		else:
-			self.impl = decimal.Decimal(val).quantize(_quantize_exp)
-	
-	def __repr__(self):
-		return '<Fixed {}>'.format(str(self.impl))
-	def pp(self, dp):
-		"""Pretty print to specified number of decimal places"""
-		return format(self.impl, '.{}f'.format(dp))
-	
-	def to_rational(self):
-		"""Convert to an instance of Rational"""
-		from pyRCV2.numbers import Rational
-		return Rational(self.impl)
-	
-	@compatible_types
-	def __add__(self, other):
-		return Fixed(self.impl + other.impl)
-	@compatible_types
-	def __sub__(self, other):
-		return Fixed(self.impl - other.impl)
-	@compatible_types
-	def __mul__(self, other):
-		return Fixed(self.impl * other.impl)
-	@compatible_types
-	def __truediv__(self, other):
-		return Fixed(self.impl / other.impl)
-	
-	@compatible_types
-	def __eq__(self, other):
-		return self.impl == other.impl
-	@compatible_types
-	def __ne__(self, other):
-		return self.impl != other.impl
-	@compatible_types
-	def __gt__(self, other):
-		return self.impl > other.impl
-	@compatible_types
-	def __ge__(self, other):
-		return self.impl >= other.impl
-	@compatible_types
-	def __lt__(self, other):
-		return self.impl < other.impl
-	@compatible_types
-	def __le__(self, other):
-		return self.impl <= other.impl
-	
-	def __floor__(self):
-		return Fixed(math.floor(self.impl))
+	@classmethod
+	def _to_impl(cls, value):
+		"""Overrides BasePyNum._to_impl"""
+		return decimal.Decimal(value).quantize(_quantize_exp)
 	
 	def round(self, dps, mode):
-		"""Round to the specified number of decimal places, using the ROUND_* mode specified"""
+		"""Implements BaseNum.round"""
 		return Fixed(self.impl.quantize(decimal.Decimal('10') ** -dps, mode))
diff --git a/pyRCV2/numbers/native_js.py b/pyRCV2/numbers/native_js.py
index 341c7bd..54a0b6c 100644
--- a/pyRCV2/numbers/native_js.py
+++ b/pyRCV2/numbers/native_js.py
@@ -1,5 +1,5 @@
 #   pyRCV2: Preferential vote counting
-#   Copyright © 2020  Lee Yingtong Li (RunasSudo)
+#   Copyright © 2020–2021  Lee Yingtong Li (RunasSudo)
 #
 #   This program is free software: you can redistribute it and/or modify
 #   it under the terms of the GNU Affero General Public License as published by
@@ -14,65 +14,77 @@
 #   You should have received a copy of the GNU Affero General Public License
 #   along with this program.  If not, see <https://www.gnu.org/licenses/>.
 
-class Native:
+from pyRCV2.numbers.base import BaseNum, compatible_types
+
+class Native(BaseNum):
 	"""
 	Wrapper for JS numbers (naive floating-point arithmetic)
 	"""
 	
-	ROUND_DOWN = 0
-	ROUND_HALF_UP = 1
-	ROUND_HALF_EVEN = 2
-	ROUND_UP = 3
-	
-	def __init__(self, val):
-		if isinstance(val, Native):
-			self.impl = val.impl
-		else:
-			self.impl = parseFloat(val)
+	@classmethod
+	def _to_impl(cls, value):
+		"""Implements BaseNum._to_impl"""
+		return parseFloat(value)
 	
 	def pp(self, dp):
-		"""Pretty print to specified number of decimal places"""
+		"""Implements BaseNum.pp"""
 		return self.impl.toFixed(dp)
 	
-	def to_rational(self):
-		"""Convert to an instance of Rational"""
-		from pyRCV2.numbers import Rational
-		return Rational(self.impl)
-	
-	def __add__(self, other):
-		return Native(self.impl + other.impl)
-	def __sub__(self, other):
-		return Native(self.impl - other.impl)
-	def __mul__(self, other):
-		return Native(self.impl * other.impl)
-	def __div__(self, other):
-		return Native(self.impl / other.impl)
+	@classmethod
+	def _add_impl(cls, i1, i2):
+		"""Implements BaseNum._add_impl"""
+		return i1 + i2
+	@classmethod
+	def _sub_impl(cls, i1, i2):
+		"""Implements BaseNum._sub_impl"""
+		return i1 - i2
+	@classmethod
+	def _mul_impl(cls, i1, i2):
+		"""Implements BaseNum._mul_impl"""
+		return i1 * i2
+	@classmethod
+	def _truediv_impl(cls, i1, i2):
+		"""Implements BaseNum._truediv_impl"""
+		return i1 / i2
 	
+	@compatible_types
 	def __eq__(self, other):
+		"""Implements BaseNum.__eq__"""
 		return self.impl == other.impl
+	@compatible_types
 	def __ne__(self, other):
+		"""Overrides BaseNum.__ne__"""
 		return self.impl != other.impl
+	@compatible_types
 	def __gt__(self, other):
+		"""Implements BaseNum.__gt__"""
 		return self.impl > other.impl
+	@compatible_types
 	def __ge__(self, other):
+		"""Implements BaseNum.__ge__"""
 		return self.impl >= other.impl
+	@compatible_types
 	def __lt__(self, other):
+		"""Implements BaseNum.__lt__"""
 		return self.impl < other.impl
+	@compatible_types
 	def __le__(self, other):
+		"""Implements BaseNum.__le__"""
 		return self.impl <= other.impl
 	
 	def __floor__(self):
+		"""Overrides BaseNum.__floor__"""
 		return Native(Math.floor(self.impl))
 	
 	def round(self, dps, mode):
-		"""Round to the specified number of decimal places, using the ROUND_* mode specified"""
+		"""Implements BaseNum.round"""
 		if mode == Native.ROUND_DOWN:
 			return Native(Math.floor(self.impl * Math.pow(10, dps)) / Math.pow(10, dps))
 		elif mode == Native.ROUND_HALF_UP:
 			return Native(Math.round(self.impl * Math.pow(10, dps)) / Math.pow(10, dps))
 		elif mode == Native.ROUND_HALF_EVEN:
-			raise Exception('ROUND_HALF_EVEN is not implemented in JS Native context')
+			raise NotImplementedError('ROUND_HALF_EVEN is not implemented in JS Native context')
 		elif mode == Native.ROUND_UP:
 			return Native(Math.ceil(self.impl * Math.pow(10, dps)) / Math.pow(10, dps))
 		else:
-			raise Exception('Invalid rounding mode')
+			raise ValueError('Invalid rounding mode')
diff --git a/pyRCV2/numbers/native_py.py b/pyRCV2/numbers/native_py.py
index 778e9d0..d4c9e07 100644
--- a/pyRCV2/numbers/native_py.py
+++ b/pyRCV2/numbers/native_py.py
@@ -1,5 +1,5 @@
 #   pyRCV2: Preferential vote counting
-#   Copyright © 2020  Lee Yingtong Li (RunasSudo)
+#   Copyright © 2020–2021  Lee Yingtong Li (RunasSudo)
 #
 #   This program is free software: you can redistribute it and/or modify
 #   it under the terms of the GNU Affero General Public License as published by
@@ -14,89 +14,27 @@
 #   You should have received a copy of the GNU Affero General Public License
 #   along with this program.  If not, see <https://www.gnu.org/licenses/>.
 
-import functools
+from pyRCV2.numbers.base import BasePyNum, compatible_types
+
 import math
 
-def compatible_types(f):
-	@functools.wraps(f)
-	def wrapper(self, other):
-		if not isinstance(other, Native):
-			raise ValueError('Attempt to operate on incompatible types')
-		return f(self, other)
-	return wrapper
-
-class Native:
+class Native(BasePyNum):
 	"""
 	Wrapper for Python float (naive floating-point arithmetic)
 	"""
 	
-	ROUND_DOWN = 0
-	ROUND_HALF_UP = 1
-	ROUND_HALF_EVEN = 2
-	ROUND_UP = 3
-	
-	def __init__(self, val):
-		if isinstance(val, Native):
-			self.impl = val.impl
-		else:
-			self.impl = float(val)
-	
-	def __repr__(self):
-		return '<Native {}>'.format(str(self.impl))
-	def pp(self, dp):
-		"""Pretty print to specified number of decimal places"""
-		return format(self.impl, '.{}f'.format(dp))
-	
-	def to_rational(self):
-		"""Convert to an instance of Rational"""
-		from pyRCV2.numbers import Rational
-		return Rational(self.impl)
-	
-	@compatible_types
-	def __add__(self, other):
-		return Native(self.impl + other.impl)
-	@compatible_types
-	def __sub__(self, other):
-		return Native(self.impl - other.impl)
-	@compatible_types
-	def __mul__(self, other):
-		return Native(self.impl * other.impl)
-	@compatible_types
-	def __truediv__(self, other):
-		return Native(self.impl / other.impl)
-	
-	@compatible_types
-	def __eq__(self, other):
-		return self.impl == other.impl
-	@compatible_types
-	def __ne__(self, other):
-		return self.impl != other.impl
-	@compatible_types
-	def __gt__(self, other):
-		return self.impl > other.impl
-	@compatible_types
-	def __ge__(self, other):
-		return self.impl >= other.impl
-	@compatible_types
-	def __lt__(self, other):
-		return self.impl < other.impl
-	@compatible_types
-	def __le__(self, other):
-		return self.impl <= other.impl
-	
-	def __floor__(self):
-		return Native(math.floor(self.impl))
+	_py_class = float # For BasePyNum
 	
 	def round(self, dps, mode):
-		"""Round to the specified number of decimal places, using the ROUND_* mode specified"""
+		"""Implements BaseNum.round"""
 		factor = 10 ** dps
 		if mode == Native.ROUND_DOWN:
 			return Native(math.floor(self.impl * factor) / factor)
 		elif mode == Native.ROUND_HALF_UP:
-			raise Exception('ROUND_HALF_UP is not implemented in Python Native context')
+			raise NotImplementedError('ROUND_HALF_UP is not implemented in Python Native context')
 		elif mode == Native.ROUND_HALF_EVEN:
 			return Native(round(self.impl * factor) / factor)
 		elif mode == Native.ROUND_UP:
 			return Native(math.ceil(self.impl * factor) / factor)
 		else:
-			raise Exception('Invalid rounding mode')
+			raise ValueError('Invalid rounding mode')
diff --git a/pyRCV2/numbers/rational_js.py b/pyRCV2/numbers/rational_js.py
index b935510..2f76fc7 100644
--- a/pyRCV2/numbers/rational_js.py
+++ b/pyRCV2/numbers/rational_js.py
@@ -1,5 +1,5 @@
 #   pyRCV2: Preferential vote counting
-#   Copyright © 2020  Lee Yingtong Li (RunasSudo)
+#   Copyright © 2020–2021  Lee Yingtong Li (RunasSudo)
 #
 #   This program is free software: you can redistribute it and/or modify
 #   it under the terms of the GNU Affero General Public License as published by
@@ -14,76 +14,75 @@
 #   You should have received a copy of the GNU Affero General Public License
 #   along with this program.  If not, see <https://www.gnu.org/licenses/>.
 
-class Rational:
+from pyRCV2.numbers.base import BaseNum, compatible_types
+
+class Rational(BaseNum):
 	"""
 	Wrapper for BigRational.js (rational arithmetic)
 	"""
 	
-	ROUND_DOWN = 0
-	ROUND_HALF_UP = 1
-	ROUND_HALF_EVEN = 2
-	ROUND_UP = 3
-	
-	def __init__(self, val):
-		if isinstance(val, Rational):
-			self.impl = val.impl
-		else:
-			self.impl = bigRat(val)
+	@classmethod
+	def _to_impl(cls, value):
+		"""Implements BaseNum._to_impl"""
+		return bigRat(value)
 	
 	def pp(self, dp):
-		"""
-		Pretty print to specified number of decimal places
-		This will fail for numbers which cannot be represented as a JavaScript number
-		"""
+		"""Implements BaseNum.pp"""
+		# FIXME: This will fail for numbers which cannot be represented as a JavaScript number
 		return self.impl.valueOf().toFixed(dp)
 	
-	def to_rational(self):
-		return self
-	
-	def to_num(self):
-		"""
-		Convert to an instance of Num
-		"""
-		from pyRCV2.numbers import Num
-		__pragma__('opov')
-		return Num(self.impl.numerator.toString()) / Num(self.impl.denominator.toString())
-		__pragma__('noopov')
-	
-	def __add__(self, other):
-		return Rational(self.impl.add(other.impl))
-	def __sub__(self, other):
-		return Rational(self.impl.subtract(other.impl))
-	def __mul__(self, other):
-		return Rational(self.impl.multiply(other.impl))
-	def __div__(self, other):
-		return Rational(self.impl.divide(other.impl))
+	@classmethod
+	def _add_impl(cls, i1, i2):
+		"""Implements BaseNum._add_impl"""
+		return i1.add(i2)
+	@classmethod
+	def _sub_impl(cls, i1, i2):
+		"""Implements BaseNum._sub_impl"""
+		return i1.subtract(i2)
+	@classmethod
+	def _mul_impl(cls, i1, i2):
+		"""Implements BaseNum._mul_impl"""
+		return i1.multiply(i2)
+	@classmethod
+	def _truediv_impl(cls, i1, i2):
+		"""Implements BaseNum._truediv_impl"""
+		return i1.divide(i2)
 	
+	@compatible_types
 	def __eq__(self, other):
+		"""Implements BaseNum.__eq__"""
 		return self.impl.equals(other.impl)
-	def __ne__(self, other):
-		return not self.impl.equals(other.impl)
+	@compatible_types
 	def __gt__(self, other):
+		"""Implements BaseNum.__gt__"""
 		return self.impl.greater(other.impl)
+	@compatible_types
 	def __ge__(self, other):
+		"""Implements BaseNum.__ge__"""
 		return self.impl.greaterOrEquals(other.impl)
+	@compatible_types
 	def __lt__(self, other):
+		"""Implements BaseNum.__lt__"""
 		return self.impl.lesser(other.impl)
+	@compatible_types
 	def __le__(self, other):
+		"""Implements BaseNum.__le__"""
 		return self.impl.lesserOrEquals(other.impl)
 	
 	def __floor__(self):
+		"""Overrides BaseNum.__floor__"""
 		return Rational(self.impl.floor())
 	
 	def round(self, dps, mode):
-		"""Round to the specified number of decimal places, using the ROUND_* mode specified"""
+		"""Implements BaseNum.round"""
 		factor = bigRat(10).pow(dps)
 		if mode == Rational.ROUND_DOWN:
 			return Rational(self.impl.multiply(factor).floor().divide(factor))
 		elif mode == Rational.ROUND_HALF_UP:
 			return Rational(self.impl.multiply(factor).round().divide(factor))
 		elif mode == Rational.ROUND_HALF_EVEN:
-			raise Exception('ROUND_HALF_EVEN is not implemented in JS Native context')
+			raise NotImplementedError('ROUND_HALF_EVEN is not implemented in JS Native context')
 		elif mode == Rational.ROUND_UP:
 			return Rational(self.impl.multiply(factor).ceil().divide(factor))
 		else:
-			raise Exception('Invalid rounding mode')
+			raise ValueError('Invalid rounding mode')
diff --git a/pyRCV2/numbers/rational_py.py b/pyRCV2/numbers/rational_py.py
index 2155250..c7b8dce 100644
--- a/pyRCV2/numbers/rational_py.py
+++ b/pyRCV2/numbers/rational_py.py
@@ -1,5 +1,5 @@
 #   pyRCV2: Preferential vote counting
-#   Copyright © 2020  Lee Yingtong Li (RunasSudo)
+#   Copyright © 2020–2021  Lee Yingtong Li (RunasSudo)
 #
 #   This program is free software: you can redistribute it and/or modify
 #   it under the terms of the GNU Affero General Public License as published by
@@ -14,98 +14,33 @@
 #   You should have received a copy of the GNU Affero General Public License
 #   along with this program.  If not, see <https://www.gnu.org/licenses/>.
 
+from pyRCV2.numbers.base import BasePyNum, compatible_types
+
 from fractions import Fraction
-import functools
 import math
 
-def compatible_types(f):
-	@functools.wraps(f)
-	def wrapper(self, other):
-		if not isinstance(other, Rational):
-			raise ValueError('Attempt to operate on incompatible types')
-		return f(self, other)
-	return wrapper
-
-class Rational:
+class Rational(BasePyNum):
 	"""
 	Wrapper for Python Fraction (rational arithmetic)
 	"""
 	
-	ROUND_DOWN = 0
-	ROUND_HALF_UP = 1
-	ROUND_HALF_EVEN = 2
-	ROUND_UP = 3
+	_py_class = Fraction # For BasePyNum
 	
-	def __init__(self, val):
-		if isinstance(val, Rational):
-			self.impl = val.impl
-		else:
-			self.impl = Fraction(val)
-	
-	def __repr__(self):
-		return '<Rational {}>'.format(str(self.impl))
 	def pp(self, dp):
-		"""
-		Pretty print to specified number of decimal places
-		"""
+		"""Overrides BasePyNum.pp"""
 		# TODO: Work out if there is a better way of doing this
 		return format(float(self.impl), '.{}f'.format(dp))
 	
-	def to_rational(self):
-		return self
-	
-	def to_num(self):
-		"""
-		Convert to an instance of Num
-		"""
-		from pyRCV2.numbers import Num
-		return Num(self.impl.numerator) / Num(self.impl.denominator)
-	
-	@compatible_types
-	def __add__(self, other):
-		return Rational(self.impl + other.impl)
-	@compatible_types
-	def __sub__(self, other):
-		return Rational(self.impl - other.impl)
-	@compatible_types
-	def __mul__(self, other):
-		return Rational(self.impl * other.impl)
-	@compatible_types
-	def __truediv__(self, other):
-		return Rational(self.impl / other.impl)
-	
-	@compatible_types
-	def __eq__(self, other):
-		return self.impl == other.impl
-	@compatible_types
-	def __ne__(self, other):
-		return self.impl != other.impl
-	@compatible_types
-	def __gt__(self, other):
-		return self.impl > other.impl
-	@compatible_types
-	def __ge__(self, other):
-		return self.impl >= other.impl
-	@compatible_types
-	def __lt__(self, other):
-		return self.impl < other.impl
-	@compatible_types
-	def __le__(self, other):
-		return self.impl <= other.impl
-	
-	def __floor__(self):
-		return Rational(math.floor(self.impl))
-	
 	def round(self, dps, mode):
-		"""Round to the specified number of decimal places, using the ROUND_* mode specified"""
+		"""Implements BaseNum.round"""
 		factor = Fraction(10) ** dps
 		if mode == Rational.ROUND_DOWN:
 			return Rational(math.floor(self.impl * factor) / factor)
 		elif mode == Rational.ROUND_HALF_UP:
-			raise Exception('ROUND_HALF_UP is not implemented in Python Rational context')
+			raise NotImplementedError('ROUND_HALF_UP is not implemented in Python Rational context')
 		elif mode == Rational.ROUND_HALF_EVEN:
 			return Rational(round(self.impl * factor) / factor)
 		elif mode == Rational.ROUND_UP:
 			return Rational(math.ceil(self.impl * factor) / factor)
 		else:
-			raise Exception('Invalid rounding mode')
+			raise ValueError('Invalid rounding mode')