.editorconfig

+root = true
+
+[*]
+charset = utf-8
+end_of_line = lf
+insert_final_newline = true
+indent_style = tab
+
+[*.{yml,yaml,cfg}]
+indent_style = space
+indent_size = 2

.gitignore

+*.py[co]
+
+*.tar
+*.tar.*
+*.whl
+
+*_cache

.gitlint

+[general]
+ignore=body-trailing-whitespace,body-is-missing
+regex-style-search=True
+
+[author-valid-email]
+regex=@[a-zA-Z0-9][a-zA-Z0-9-]{0,61}[a-zA-Z0-9](\.[a-zA-Z0-9][a-zA-Z0-9-]{0,61}[a-zA-Z0-9])+$
+
+[ignore-body-lines]
+regex="^(Fixes|Closes):?\s+[#][0-9]+"
+
+# vim:ft=cfg

.pre-commit-config.yaml

+default_stages: [commit]
+repos:
+
+- repo: meta
+  hooks:
+  - id: check-hooks-apply
+  - id: check-useless-excludes
+
+- repo: https://github.com/pre-commit/pre-commit-hooks
+  rev: v4.6.0
+  hooks:
+  - id: check-added-large-files
+  - id: check-case-conflict
+  - id: check-merge-conflict
+  - id: check-toml
+  - id: check-yaml
+  - id: debug-statements
+  - id: destroyed-symlinks
+  - id: end-of-file-fixer
+    stages: [commit, manual]
+  - id: fix-byte-order-marker
+  - id: fix-encoding-pragma
+    args: [--remove]
+  - id: mixed-line-ending
+    args: [--fix=lf]
+    stages: [commit, manual]
+  - id: trailing-whitespace
+    exclude_types: [markdown, plain-text]
+    stages: [commit, manual]
+
+- repo: https://github.com/jorisroovers/gitlint
+  rev: v0.19.1
+  hooks:
+  - id: gitlint
+
+- repo: https://code.kodo.org.uk/dom/pre-commit-hooks
+  rev: v0.6.1
+  hooks:
+  - id: check-executable-modes
+  - id: check-for-squash
+  - id: copyright-notice
+    args: [--min-size=1000]
+    files: ^kodo/.*
+    stages: [commit, manual]
+  - id: protect-first-parent
+
+- repo: https://github.com/pre-commit/pygrep-hooks
+  rev: v1.10.0
+  hooks:
+  - id: python-no-eval
+  - id: python-no-log-warn
+  - id: python-use-type-annotations
+
+- repo: https://github.com/hakancelikdev/unimport
+  rev: 1.2.1
+  hooks:
+  - id: unimport
+    args: [--remove]
+    types: []
+    types_or: [python, pyi]
+    additional_dependencies: [libcst >=0.4.0]
+    stages: [commit, manual]
+
+- repo: https://github.com/pycqa/isort
+  rev: 5.13.2
+  hooks:
+  - id: isort
+    stages: [commit, manual]
+
+- repo: https://github.com/asottile/add-trailing-comma
+  rev: v3.1.0
+  hooks:
+  - id: add-trailing-comma
+    args: [--py36-plus]
+    types: []
+    types_or: [python, pyi]
+    stages: [commit, manual]
+
+- repo: https://code.kodo.org.uk/dom/pre-commit-pytest
+  rev: v1.0
+  hooks:
+  - id: pytest
+    types_or: [python, markdown]
+    stages: [commit, manual]
+    args: [--doctest-modules, --doctest-continue-on-failure]
+  - id: pytest
+    args: [test.py]
+
+- repo: https://github.com/astral-sh/ruff-pre-commit
+  rev: v0.6.2
+  hooks:
+  - id: ruff
+    args: [--fix, --unsafe-fixes]
+
+- repo: https://github.com/pre-commit/mirrors-mypy
+  rev: v1.11.2
+  hooks:
+  - id: mypy
+    args: [--follow-imports=silent, kodo]
+    pass_filenames: false

.ruff.toml

+line-length = 92
+indent-width = 1  # Used for line length violations
+
+[lint]
+select = [
+	# pyflakes
+	# --------
+
+	# ENABLE "Undefined name %s in __all__"
+	"F822",
+
+	# ENABLE "Local variable %s ... referenced before assignment"
+	"F823",
+
+	# ENABLE "Local variable %s is assigned to but never used"
+	"F841",
+
+	# ENABLE "raise NotImplemented should be raise NotImplementedError"
+	# mypy has particular trouble with this one:
+	# https://github.com/python/mypy/issues/5710
+	"F901",
+
+	# pycodestyle
+	# -----------
+
+	# Warnings not considered, many are not relevant to Python ~=3.9 and will
+	# cause syntax errors anyway, others concern whitespace which is fixed by
+	# a pre-commit hook.
+	"E",
+
+	# mccabe
+	# ------
+
+	"C90",
+
+	# pydocstyle
+	# ----------
+
+	# Missing docstrings
+	"D1",
+
+	# Whitespace Issues
+	"D2",
+
+	# ENABLE "Use “””triple double quotes”””"
+	"D300",
+
+	# First line should be descriptive, imperative and capitalised
+	"D401", "D402", "D403", "D404",
+
+	# ENABLE "Function/Method decorated with @overload shouldn’t contain a docstring"
+	"D418",
+
+	# flake8-bugbear
+	# --------------
+
+	# The bulk of bugbear's checks are useful
+	"B0",
+
+	# Various others
+	# --------------
+
+	"UP", "BLE", "FBT", "A", "COM", "C4", "DTZ", "ISC", "LOG", "G", "PIE", "T",
+	"Q", "RSE", "RET", "SLF", "SLOT", "SIM", "TD", "ANN", #"FA",
+
+	# Nice to have, needs fixing in several places though...
+	# "EM", "TCH", "PTH", "PGH",
+]
+ignore = [
+	# pycodestyle
+	# -----------
+
+	# DISABLE "Indentation contains mixed spaces and tabs"
+	# Will cause a syntax error if critical, otherwise in docstrings it is
+	# sometimes nice to use different indentation for "outer" (code) indentation
+	# and "inner" (documentation) indentation.
+	"E101",
+
+	# DISABLE "Continuation line missing indentation or outdented"
+	# "E122",
+
+	# DISABLE "Missing whitespace around bitwise or shift operator"
+	"E227",
+
+	# DISABLE "missing whitespace around arithmetic operator"
+	"E226",
+
+	# DISABLE "Line too long"
+	# Prefer B950 implementation
+	"E501",
+
+	# DISABLE "Multiple statements on one line (colon)"
+	"E701",
+
+	# DISABLE "Multiple statements on one line (def)"
+	# Doesn't work well with @overload definitions
+	# "E704",
+
+	# pydocstyle
+	# ----------
+
+	# DISABLE "Missing docstring in magic method"
+	# Magic/dunder methods are well-known
+	"D105",
+
+	# DISABLE "Missing docstring in __init__"
+	# Document basic construction in the class docstring
+	"D107",
+
+	# DISABLE "One-line docstring should fit on one line with quotes"
+	# Prefer top-and-bottom style always
+	"D200",
+
+	# DISABLE "1 blank line required before class docstring"
+	"D203",
+
+	# DISABLE "Docstring should be indented with spaces, not tabs"
+	# Tabs, absolutely always
+	"D206",
+
+	# DISABLE "Multi-line docstring summary should start at the first line"
+	"D212",
+
+	# flake8-bugbear
+	# --------------
+
+	# DISABLE "Do not use mutable data structures for argument defaults [...]"
+	# Would be nice if could take into account use as a non-mutable type
+	"B006",
+
+	# DISABLE "Loop control variable `self` overrides iterable it iterates"
+	# Bit buggy, and type checker should catch it.
+	"B020",
+
+	# DISABLE "release is an empty method in an abstract base class, [...]"
+	# Until abstract methods are optional, empty optional "abstract" methods
+	# stay
+	"B027",
+
+	# Use named-tuples (preferably class based) for data-only classes
+	# "B903",
+
+	# Replacement for E501
+	# "B950",
+
+	# flake8-return
+	# -------------
+
+	# DISABLE "missing explicit return at the end of function able to return
+	# non-None value"
+	# Mypy will report this, plugin also cannot do exhaustiveness check of match
+	# block, leading to false-positives.
+	"RET503",
+
+	# DISABLE "Missing type annotation for `%` in {method|classmethod}"
+	# Don't type 'self' or 'cls'
+	"ANN101", "ANN102",
+
+	# DISABLE "Boolean positional value in function call"
+	# Too many stdlib functions take a single positional-only boolean. ruff
+	# can't interpret function signatures to ignore these and doesn't understand
+	# types to allow-list methods.
+	"FBT003",
+
+	# DISABLE "Implicitly concatenated string literals over multiple lines"
+	# It sometimes looks better to do this than introduce unecessary
+	# parentheses.
+	"ISC002",
+
+	# Unfortunately a lot of single quotes strings used in this project already
+	"Q000",
+]
+
+[lint.per-file-ignores]
+"test*" = ["D1"]

LICENCE.txt

+
+                                 Apache License
+                           Version 2.0, January 2004
+                        http://www.apache.org/licenses/
+
+   TERMS AND CONDITIONS FOR USE, REPRODUCTION, AND DISTRIBUTION
+
+   1. Definitions.
+
+      "License" shall mean the terms and conditions for use, reproduction,
+      and distribution as defined by Sections 1 through 9 of this document.
+
+      "Licensor" shall mean the copyright owner or entity authorized by
+      the copyright owner that is granting the License.
+
+      "Legal Entity" shall mean the union of the acting entity and all
+      other entities that control, are controlled by, or are under common
+      control with that entity. For the purposes of this definition,
+      "control" means (i) the power, direct or indirect, to cause the
+      direction or management of such entity, whether by contract or
+      otherwise, or (ii) ownership of fifty percent (50%) or more of the
+      outstanding shares, or (iii) beneficial ownership of such entity.
+
+      "You" (or "Your") shall mean an individual or Legal Entity
+      exercising permissions granted by this License.
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+      "Work" shall mean the work of authorship, whether in Source or
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+      the conditions stated in this License.
+
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+      any Contribution intentionally submitted for inclusion in the Work
+      by You to the Licensor shall be under the terms and conditions of
+      this License, without any additional terms or conditions.
+      Notwithstanding the above, nothing herein shall supersede or modify
+      the terms of any separate license agreement you may have executed
+      with Licensor regarding such Contributions.
+
+   6. Trademarks. This License does not grant permission to use the trade
+      names, trademarks, service marks, or product names of the Licensor,
+      except as required for reasonable and customary use in describing the
+      origin of the Work and reproducing the content of the NOTICE file.
+
+   7. Disclaimer of Warranty. Unless required by applicable law or
+      agreed to in writing, Licensor provides the Work (and each
+      Contributor provides its Contributions) on an "AS IS" BASIS,
+      WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or
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+   8. Limitation of Liability. In no event and under no legal theory,
+      whether in tort (including negligence), contract, or otherwise,
+      unless required by applicable law (such as deliberate and grossly
+      negligent acts) or agreed to in writing, shall any Contributor be
+      liable to You for damages, including any direct, indirect, special,
+      incidental, or consequential damages of any character arising as a
+      result of this License or out of the use or inability to use the
+      Work (including but not limited to damages for loss of goodwill,
+      work stoppage, computer failure or malfunction, or any and all
+      other commercial damages or losses), even if such Contributor
+      has been advised of the possibility of such damages.
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+   9. Accepting Warranty or Additional Liability. While redistributing
+      the Work or Derivative Works thereof, You may choose to offer,
+      and charge a fee for, acceptance of support, warranty, indemnity,
+      or other liability obligations and/or rights consistent with this
+      License. However, in accepting such obligations, You may act only
+      on Your own behalf and on Your sole responsibility, not on behalf
+      of any other Contributor, and only if You agree to indemnify,
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+
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+      boilerplate notice, with the fields enclosed by brackets "[]"
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+   Copyright [yyyy] [name of copyright owner]
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+       http://www.apache.org/licenses/LICENSE-2.0
+
+   Unless required by applicable law or agreed to in writing, software
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+   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+   See the License for the specific language governing permissions and
+   limitations under the License.

conftest.py

+"""
+Setup and configuration for pytest
+"""
+
+import time
+from unittest.mock import Mock
+
+import pytest
+
+
+@pytest.fixture(autouse=True)
+def add_time_mock(doctest_namespace: dict[str, object]) -> None:
+	"""
+	Add a doctest mock for `time.sleep()`
+	"""
+	time.sleep = Mock(return_value=None)

kodo/quantities/__init__.py

+# Copyright 2024 Dom Sekotill <dom.sekotill@kodo.org.uk>
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+"""
+Types for representing physical quantities, which have a magnitude and a unit
+
+Defining Units
+--------------
+
+Unit types for quantities are created by subclassing the `QuantityUnit` enum base:
+
+>>> class Time(QuantityUnit):
+...     MILLISECONDS = 1
+...     SECONDS = 1000
+...     MINUTES = 60 * SECONDS
+
+>>> class Distance(QuantityUnit):
+...     MILLIMETERS = 1
+...     CENTIMETERS = 10 * MILLIMETERS
+...     METERS = 100 * CENTIMETERS
+...     KILOMETERS = 1000 * METERS
+...     INCH = 24 * MILLIMETERS
+...     HALF_INCH = INCH // 2  # Hey! Hands off
+...     QUARTER_INCH = INCH // 4
+
+The enum members form units of relative size to each other. They MUST be integers so
+typically the smallest (highest precision) unit is `1` and the others are some multiple of
+it. Note that the designated 'unit' can be changed without breaking dependant code (as long
+as the code is using the quantities right).  In this case the unitary value is 0.5mm:
+
+>>> class Distance(QuantityUnit):
+...     MILLIMETERS = 2  # Scaled to allow SIXTEENTH_INCH to be an integer
+...     # [...]
+...     SIXTEENTH_INCH = 3  # 1/16″ is 1.5mm
+...     INCH = 16 * SIXTEENTH_INCH
+
+Although it would probably be easier to make the unitary value 0.1mm:
+
+>>> class Distance(QuantityUnit):
+...     MILLIMETERS = 10
+...     # [...]
+...     SIXTEENTH_INCH = 15
+...     INCH = 16 * SIXTEENTH_INCH
+
+In full:
+
+>>> class Distance(QuantityUnit):
+...     MILLIMETERS = 10
+...     CENTIMETERS = 10 * MILLIMETERS
+...     METERS = 100 * CENTIMETERS
+...     KILOMETERS = 1000 * METERS
+...     SIXTEENTH_INCH = 15
+...     INCH = 16 * SIXTEENTH_INCH
+...     HALF_INCH = 8 * SIXTEENTH_INCH
+...     QUARTER_INCH = 4 * SIXTEENTH_INCH
+
+
+Creating Physical Quantities
+----------------------------
+
+A physical quantity can be created using the matrix multiplication operator "@" with a
+quantity unit, e.g. 2 seconds:
+
+>>> quantity: Quantity[Time] = 2 @ Time.SECONDS
+
+Quantities of the same type relate to one another as you would expect (parentheses for
+clarity):
+
+>>> assert (2 @ Time.SECONDS) == (2000 @ Time.MILLISECONDS)
+
+Note that quantities are really just integers which, at runtime, have no additional
+information attached to them. This means that Python will happily accept any `Quantity`
+wherever it would accept an integer; however static type checkers such as MyPy will complain
+about it, which is good as it is almost certainly a mistake to attempt to, for example, sum
+time and distance quantities, or sum a quantity with an arbitrary value:
+
+>>> meaningless_value = (2 @ Time.SECONDS) + (10 @ Distance.MILLIMETERS)
+
+>>> # Depending on the declaration of Distance, 100 here could be interpreted by the
+>>> # runtime as 100m, 100cm, 100/24″, or anything else...
+>>> unreliable_value = (2 @ Distance.METERS) + 100
+
+Multiplying quantities with other quantities, even of the same type, would produce
+a different unit, which is not supported.  (However, it is conceivable that it could
+be supported in the future.) The following will also fail static type checks:
+
+>>> area = (2 @ Distance.METERS) * (2 @ Distance.METERS)  # 4.0m²
+>>> speed = (100 @ Distance.METERS) / (1 @ Time.SECONDS)  # 100m/s
+
+
+Using Physical Quantities
+-------------------------
+
+At some point quantities will need to be passed through an interface of some sort where the
+unit information will be lost.  Such interfaces will define a single unit they accept; for
+instance `time.sleep()` requires an argument in seconds.  Upon reaching such an interface,
+quantities can be stripped of their scalar types and converted to the required unit with the
+right bit-shift operator ">>" or floor division operator "//":
+
+>>> delay = 2 @ Time.MINUTES
+>>> # [...]
+>>> import time
+>>> time.sleep(delay >> Time.SECONDS)
+
+With the ">>" operator the type of the resulting value is always a `float` and
+will only be precise up to the highest precision unit for a defined `QuantityUnit` type (the
+unit with a magnitude of `1`, which need not be explicitly defined).
+
+With the "//" operator the resulting type will be `int`, with whatever loss of precision
+that implies.
+
+>>> delay = 3600 @ Time.MILLISECONDS
+>>> # [...]
+>>> time.sleep(delay // Time.SECONDS)  # Will sleep for 3 seconds
+
+
+Operations on Quantities
+------------------------
+
+At runtime all quantities are a subclass of integers, so all operations that work on
+integers will work[^*] however type checkers only allow a subset of operations with certain
+types.
+
+[^*]: One small difference is multiplication by floats and division by float or int, which
+would normally return floats, returns a new integer quantity.  However division by
+a quantity returns a float.  Don't worry too much about this.
+
+Quantities may be added to or subtracted from other quantities with the same unit, returning
+a new quantity of that unit:
+
+>>> assert (2 @ Time.SECONDS) + (500 @ Time.MILLISECONDS) == (2500 @ Time.MILLISECONDS)
+
+They may be scaled by multiplying (*) and dividing (/) by unitless numeric values _only_,
+resulting in a new quantity of the same unit.  Note however that when scaling down there
+will probably be some rounding loss depending on the precision of the unit.
+
+>>> assert (2 @ Time.SECONDS) * 2 == (4 @ Time.SECONDS)
+>>> assert (2 @ Time.SECONDS) / 2 == (1 @ Time.SECONDS)
+>>> assert (2 @ Time.SECONDS) / 3 == (666 @ Time.MILLISECONDS)  # Rounded down to whole milliseconds
+
+In addition you may use _floor_ division (//) on quantities with another quantity of the
+same unit to calculate how many times it can be divided into that size.  Note when using
+single units this is equivalent to converting to an untyped value of those units, so this is
+the same as using the floor division operator with a unit value.
+
+>>> assert (10 @ Time.SECONDS) // (2 @ Time.SECONDS) == 5
+>>> assert (10 @ Time.SECONDS) // (1 @ Time.SECONDS) == 10
+>>> assert (10 @ Time.SECONDS) // Time.SECONDS == 10  # Unit may be used as a convenience
+
+To find the remainder after floor division, the modulus operator (%) returns a new quantity:
+
+>>> assert (10 @ Time.SECONDS) % (3 @ Time.SECONDS) == (1 @ Time.SECONDS)
+>>> assert (3.6 @ Time.SECONDS) % Time.SECONDS == (600 @ Time.MILLISECONDS)
+
+This pairs well with the shift and floor division operators to get the modulus values as
+floats or ints of a particular unit:
+
+>>> assert (3.6 @ Time.SECONDS) % Time.SECONDS >> Time.SECONDS == 0.6
+>>> assert (3.6 @ Time.SECONDS) % Time.SECONDS // Time.MILLISECONDS == 600
+
+
+Choice of Operators
+-------------------
+
+The operators for constructing ("@") and deconstructing (">>") quantities may seem a bit
+odd, given that what they actually do is multiply and divide the values. They were chosen to
+be visually distinct from other multiplication and division operations on quantities and
+scalar units.
+
+The matrix multiplication operator therefore replaces the scalar multiplication operator,
+while the shift operator, which looks arrow-like, is used to convert to the indicated unit.
+i.e.:
+
+>>> # quantity  (converted to)  units
+>>> delay             >>        Time.SECONDS
+3.6
+"""
+
+from __future__ import annotations
+
+import enum
+from typing import TYPE_CHECKING
+from typing import Generic
+from typing import Self
+from typing import TypeVar
+from typing import overload
+
+U = TypeVar("U", bound="QuantityUnit")
+
+
+if TYPE_CHECKING:
+	class Quantity(Generic[U]):
+		"""
+		A physical quantity of a given unit type 'U'
+		"""
+
+		def __init__(self, value: int|float|Quantity[U], /) -> None: ...
+
+		# Adding two quantities creates a new quantity
+		def __add__(self, other: Quantity[U], /) -> Quantity[U]: ...
+
+		# Subtracting a quantity from another creates a new quantity
+		def __sub__(self, other: Quantity[U], /) -> Quantity[U]: ...
+
+		# Quantities can be multiplied by unitless values to produce a new quantity
+		def __mul__(self, other: int|float, /) -> Quantity[U]: ...
+
+		# Quantities can be divided by unitless values to produce a new quantity
+		def __truediv__(self, other: int|float, /) -> Quantity[U]: ...
+
+		# Quantities can be divided by (into) quantities of the same unit to produce
+		# a unitless value (the number of whole divisions of the quantity)
+		def __floordiv__(self, other: Quantity[U], /) -> int: ...
+
+		# The remainder of a floor division with another quantity
+		def __mod__(self, other: Quantity[U], /) -> Quantity[U]: ...
+
+else:
+	# Although the runtime implementation does not use TypeVars, it is still generic to
+	# allow type subscripting.
+
+	class Quantity(int, Generic[U]):
+		"""
+		A physical quantity of a given unit type 'U'
+		"""
+
+		def __mul__(self, other: int|float, /) -> Quantity:
+			return Quantity(other.__rmul__(self))
+
+		def __truediv__(self, other: int|float, /) -> Quantity:
+			if isinstance(other, Quantity):
+				return super().__truediv__(other)
+			return Quantity(other.__rtruediv__(self))
+
+
+class QuantityUnit(enum.Enum):
+	"""
+	Enum base class for units
+	"""
+
+	if TYPE_CHECKING:
+		@property
+		def value(self) -> int: ...  # noqa: D102
+
+	def __rmatmul__(self, scalar: float|int) -> Quantity[Self]:
+		return Quantity(self.value * scalar)
+
+	def __rrshift__(self, quantity: Quantity[Self]) -> float:
+		return self.value.__rtruediv__(quantity)  # type: ignore[operator]
+
+	def __rfloordiv__(self, quantity: Quantity[Self]) -> int:
+		return quantity // self.value  # type: ignore[operator,no-any-return]
+
+	def __rmod__(self, quantity: Quantity[Self]) -> Quantity[Self]:
+		return Quantity(quantity % self.value)  # type: ignore[operator]

pyproject.toml

+[build-system]
+requires = ["flit_core ~=3.8"]
+build-backend = "flit_core.buildapi"
+
+[[project.authors]]
+name = "Dom Sekotill"
+email = "dom.sekotill@kodo.org.uk"
+
+[project]
+name = "kodo.quantities"
+version = "0.1.0"
+description = "Types for representing physical quantities, which have a magnitude and a unit"
+license = {file = "LICENCE.txt"}
+
+classifiers = [
+	"Development Status :: 4 - Beta",
+	"Intended Audience :: Developers",
+	"License :: OSI Approved :: Apache Software License",
+	"Programming Language :: Python :: 3.11",
+	"Programming Language :: Python :: 3.12",
+	"Typing :: Typed",
+]
+
+requires-python = "~=3.11"
+
+[project.urls]
+Source = "https://code.kodo.org.uk/dom/python-quantities"
+Issues = "https://code.kodo.org.uk/dom/python-quantities/-/issues"
+
+
+[tool.isort]
+force_single_line = true
+line_length = 92
+
+
+[tool.unimport]
+ignore-init = true
+
+
+[tool.mypy]
+strict = true
+namespace_packages = true
+explicit_package_bases = true
+warn_unused_configs = true
+warn_unreachable = true

test.py

+"""
+Tests for quantities
+"""
+
+from typing import TYPE_CHECKING
+
+from kodo.quantities import QuantityUnit
+
+
+class Time(QuantityUnit):
+
+	MS = 10
+	S = 1000 * MS
+
+
+def test_add() -> None:
+	assert (1500 @ Time.MS) + (500 @ Time.MS) == (2000 @ Time.MS)
+	assert (1500 @ Time.MS) - (500 @ Time.MS) == (1000 @ Time.MS)
+
+
+def test_multiplication() -> None:
+	assert (1800 @ Time.MS) * 2 == (3600 @ Time.MS)
+	assert (3600 @ Time.MS) * 0.5 == (1800 @ Time.MS)
+
+	assert (3600 @ Time.MS) / 2 == (1800 @ Time.MS)
+	assert (1800 @ Time.MS) / 0.5 == (3600 @ Time.MS)
+
+
+def test_division_by_quantity() -> None:
+	assert (3600 @ Time.MS) // (1 @ Time.S) == 3
+	assert isinstance((3 @ Time.S) // (1 @ Time.S), int)
+
+	assert (3600 @ Time.MS) // Time.S == 3
+	assert isinstance((3 @ Time.S) // Time.S, int)
+
+
+def test_modulus() -> None:
+	assert (3600 @ Time.MS) % (2 @ Time.S) == 1600 @ Time.MS
+	assert (3600 @ Time.MS) % Time.S == 600 @ Time.MS
+
+
+if TYPE_CHECKING:
+	def type_checks() -> None:
+		# Checks for type checker false negatives
+		#
+		# All the following should result in an error when checked with mypy or pyright; the
+		# errors are suppressed but if they are not raised the suppression itself will cause
+		# mypy to raise an error in strict mode.
+
+		_ = (1 @ Time.S) + 3  # type: ignore[operator]
+		_ = (1 @ Time.S) - 3.0  # type: ignore[operator]
+
+		_ = (1 @ Time.S) * (1 @ Time.S)  # type: ignore[operator]
+		_ = (1 @ Time.S) / (1 @ Time.S)  # type: ignore[operator]
+
+		_ = (1 @ Time.S) // 2  # type: ignore[operator]
+		_ = (1 @ Time.S) // 2.0  # type: ignore[operator]