Switch to Decimal based values

.bandit

@@ -0,0 +1,2 @@
+[bandit]
+exclude: tests

.editorconfig

@@ -0,0 +1,18 @@
+# http://editorconfig.org
+
+root = true
+
+[*]
+indent_style = space
+indent_size = 4
+trim_trailing_whitespace = true
+insert_final_newline = true
+charset = utf-8
+end_of_line = lf
+max_line_length = 88
+
+[*.{json,yml,yaml}]
+indent_size = 2
+
+[LICENSE]
+insert_final_newline = false

.github/workflows/ci.yml

@@ -11,23 +11,31 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - uses: actions/setup-python@v1
-      - uses: actions/checkout@v1
+      - uses: actions/checkout@v2
       - run: python -m pip install isort
       - run: isort --check-only --diff --recursive .
 
+  flake8:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/setup-python@v1
+      - uses: actions/checkout@v2
+      - run: python -m pip install flake8
+      - run: flake8 .
+
   pydocstyle:
     runs-on: ubuntu-latest
     steps:
       - uses: actions/setup-python@v1
-      - uses: actions/checkout@v1
+      - uses: actions/checkout@v2
       - run: python -m pip install pydocstyle
       - run: pydocstyle .
 
   black:
     runs-on: ubuntu-latest
     steps:
       - uses: actions/setup-python@v1
-      - uses: actions/checkout@v1
+      - uses: actions/checkout@v2
       - run: python -m pip install black
       - run: black --check --diff .
 
@@ -36,22 +44,23 @@ jobs:
       - isort
       - pydocstyle
       - black
+      - flake8
     strategy:
       matrix:
         os:
           - ubuntu-latest
+          - windows-latest
+          - macos-latest
         python-version:
-          - 3.5
-          - 3.6
           - 3.7
           - 3.8
     runs-on: ${{ matrix.os }}
     steps:
       - name: Set up Python ${{ matrix.python-version }}
-        uses: actions/setup-python@v1.1.1
+        uses: actions/setup-python@v1
         with:
           python-version: ${{ matrix.python-version }}
-      - uses: actions/checkout@v1
+      - uses: actions/checkout@v2
       - run: python -m pip install --upgrade setuptools wheel codecov
       - run: python setup.py test
       - run: codecov

.gitignore

@@ -9,3 +9,4 @@ include/
 lib/
 docs/_build/
 .coverage
+htmlcov/

LICENSE

@@ -1,6 +1,6 @@
 The MIT License (MIT)
 
-Copyright (c) 2014 Adam Coddington
+Copyright (c) 2020 Johannes Hoppe
 
 Permission is hereby granted, free of charge, to any person obtaining a copy
 of this software and associated documentation files (the "Software"), to deal

README.rst

@@ -1,55 +1,86 @@
-.. image:: https://travis-ci.org/coddingtonbear/python-measurement.svg?branch=master
-   :target: https://travis-ci.org/coddingtonbear/python-measurement
+==================
+Python measurement
+==================
 
-Easily use and manipulate unit-aware measurement objects in Python.
+**High precision unit-aware measurement objects in Python.**
 
-`django.contrib.gis.measure <https://github.com/django/django/blob/master/django/contrib/gis/measure.py>`_
-has these wonderful 'Distance' objects that can be used not only for storing a
-unit-aware distance measurement, but also for converting between different
-units and adding/subtracting these objects from one another.
+    >>> from measurement import measures
+    >>> measures.Distance("12 megaparsec")["British yard"]
+    Decimal('404948208659679393828910.8771')
 
-This module not only provides those Distance and Area measurement
-objects, but also other measurements including:
+This package provides a large reference collection of various measure and
+their corresponding SI (Metric), US or Imperial units. Its high precision
+supports use cases all the way from quantum mechanics to astrophysics.
 
-- Energy
-- Speed
-- Temperature
-- Time
-- Volume
-- Weight
+- Documentation for python-measurement is available an
+  `ReadTheDocs <https://python-measurement.readthedocs.org/>`_.
+- Please post issues on
+  `Github <https://github.com/coddingtonbear/python-measurement/issues>`_.
 
-Example:
+Installation
+============
 
-.. code-block:: python
+You can install the latest version of the package with Pip::
 
-   >>> from measurement.measures import Weight
-   >>> weight_1 = Weight(lb=125)
-   >>> weight_2 = Weight(kg=40)
-   >>> added_together = weight_1 + weight_2
-   >>> added_together
-   Weight(lb=213.184976807)
-   >>> added_together.kg  # Maybe I actually need this value in kg?
-   96.699
+    python3 -m pip install measurement
 
-.. warning::
-   Measurements are stored internally by converting them to a
-   floating-point number of a (generally) reasonable SI unit.  Given that 
-   floating-point numbers are very slightly lossy, you should be aware of
-   any inaccuracies that this might cause.
+Usage
+=====
 
-   TLDR: Do not use this in
-   `navigation algorithms guiding probes into the atmosphere of extraterrestrial worlds <http://en.wikipedia.org/wiki/Mars_Climate_Orbiter>`_.
+Using Measurement Objects
+-------------------------
 
-- Documentation for python-measurement is available an
-  `ReadTheDocs <https://python-measurement.readthedocs.org/>`_.
-- Please post issues on
-  `Github <https://github.com/coddingtonbear/python-measurement/issues>`_.
-- Test status available on
-  `Travis-CI <https://travis-ci.org/coddingtonbear/python-measurement>`_.
+You can import any of the above measures from `measurement.measures`
+and use it for easily handling measurements like so:
+
+    >>> from measurement.measures import Mass
+    >>> m = Mass(lb=135) # Represents 135 lbs
+    >>> print(m)
+    135 lb
+    >>> print(m["long ton"])
+    0.06027063971456692913385826772
+
+You can create a measurement unit using any compatible unit and can transform
+it into any compatible unit.  See :doc:`measures` for information about which
+units are supported by which measures.
+
+.. seealso::
+    Should you be planing to go to Mars, you might need to increase your
+    `decimal precision`_, like so:
+
+        >>> import decimal
+        >>> decimal.getcontext().prec = 28
+
+.. _decimal precision: https://docs.python.org/3.8/library/decimal.html
+
+Guessing Measurements
+---------------------
+
+If you happen to be in a situation where you are processing a list of
+value/unit pairs (like you might find at the beginning of a recipe), you can
+use the `guess` function to give you a measurement object.:
+
+    >>> from measurement.utils import guess
+    >>> m = guess(10, "mg")
+    >>> print(repr(m))
+    Mass(gram="0.010")
 
+By default, this will check all built-in measures, and will return the first
+measure having an appropriate unit.  You may want to constrain the list of
+measures checked (or your own measurement classes, too) to make sure
+that your measurement is not mis-guessed, and you can do that by specifying
+the ``measures`` keyword argument:
 
+    >>> from measurement.measures import Distance, Temperature, Volume
+    >>> m = guess(24, "°F", measures=[Distance, Volume, Temperature])
+    >>> print(repr(m))
+    Temperature(fahrenheit="24.00000000000000000000000008")
 
-.. image:: https://d2weczhvl823v0.cloudfront.net/coddingtonbear/python-measurement/trend.png
-   :alt: Bitdeli badge
-   :target: https://bitdeli.com/free
+If no match is found, a :class:`ValueError` exception will be raised.
 
+.. note::
+   It is absolutely possible for this to misguess due to common measurement
+   abbreviations overlapping -- for example, both Temperature and Energy
+   accept the argument ``c`` for representing degrees celsius and calories
+   respectively.  It is advisible that you constrain the list of measurements
+   to check to ones that you would consider appropriate for your input data.

docs/conf.py

@@ -1,21 +1,49 @@
 """Sphinx configuration file."""
+import inspect
+
 from pkg_resources import get_distribution
 
+from measurement.base import AbstractMeasure
+
 project = "python-measurement"
-copyright = "2013, Adam Coddington"
+copyright = "2020, Johannes Hoppe"
 release = get_distribution("measurement").version
 version = ".".join(release.split(".")[:2])
+html_theme = "python_docs_theme"
 
 master_doc = "index"
 
+html_logo = "caliper.svg"
+
 extensions = [
     "sphinx.ext.autodoc",
     "sphinx.ext.viewcode",
     "sphinx.ext.napoleon",
     "sphinx.ext.intersphinx",
     "sphinx.ext.doctest",
+    "sphinx.ext.inheritance_diagram",
 ]
 
 intersphinx_mapping = {
     "python": ("https://docs.python.org/3", None),
 }
+
+inheritance_graph_attrs = dict(rankdir="TB")
+
+graphviz_output_format = "svg"
+
+autodoc_member_order = "bysource"
+
+
+def process_measures(app, what, name, obj, options, lines):
+    if inspect.isclass(obj) and issubclass(obj, AbstractMeasure):
+        lines.append("**Supported Units:**")
+        lines.extend(
+            f"    :{obj._attr_to_unit(name)}: {', '.join(value.symbols)}"
+            for name, value in obj._org_units.items()
+        )
+    return lines
+
+
+def setup(app):
+    app.connect("autodoc-process-docstring", process_measures)

docs/custom_measures.rst

@@ -0,0 +1,12 @@
+Custom Measures
+===============
+
+API reference
+-------------
+
+.. inheritance-diagram:: measurement.base
+
+.. automodule:: measurement.base
+  :show-inheritance:
+  :members:
+  :inherited-members: