The need to represent instances of money frequently arises in software
development, particularly any financial/economics software. To
address that need, the py-moneyed package provides the classes of
Money and Currency, at a level more useful than just using Python's
Decimal class, or ($DEITY forbid) the float primitive. The package is
meant to be stand-alone and easy to either use directly, or subclass
further. py-moneyed is BSD-licensed.
Some of the py-moneyed code was first derived from python-money
available via this URL: http://code.google.com/p/python-money/ Because
that Google Code version has been inactive since May 2008, I forked it
and modified it for my needs in 2010. Compared to python-money, major
changes here in py-moneyed include separating it from Django usage,
tightening types handling in operators, a complete suite of unit
tests, PEP8 adherence, providing a setup.py, and local currency
formatting/display.
Usage
-----
On to the code! The Money class is instantiated with:
- An amount which can be of type string, float, or Decimal.
- A currency, which usually is specified by the three-capital-letters
ISO currency code, e.g. USD, EUR, CNY, and so on.
For example,
::
from moneyed.classes import Money
sale_price_today = Money(amount='99.99', currency='USD')
The Money class also provides operators with type checking, matching
currency checking, and sensible dimensional behavior, e.g. you cannot
multiply two Money instances, nor can you add a Money instance to a
non-Money number; dividing a Money instance by another results in a
Decimal value, etc.
The Currency class is provided with a complete dictionary of ISO 4217
currencies data, each key (e.g. 'USD') mapping to a Currency instance
with ISO numeric code, canonical name in English, and countries using
the currency. Thanks to the python-money developers for their
(possibly tedious) data-entry of the ISO codes!
Testing
--------
Unit-tests have been provided, and can be run with tox_ (recommended)
or just py.test.
If you don't have tox installed on your system, it's a modern Python
tool to automate running tests and deployment; install it to your
global Python environment with:
::
sudo pip install tox
Then you can activate a virtualenv (any will do - by design tox will
not run from your globally-installed python), cd to the py-moneyed
source directory then run the tests at the shell:
::
cd where/py-moneyed-source/is
tox
The py-moneyed package has been tested with Python 2.6; it should work
with Python 2.x but I haven't tried other versions yet. Should you
use py-moneyed with other Python versions, please let me know if you
are successful or not.
.. _tox: http://tox.testrun.org/latest/
Future
------
Future versions of py-moneyed may provide currency conversions or
other capabilities, dependent on feedback and usage.