A Python implementation of Accounting Patterns framework by Martin Fowler. It may not necessarily represent MF's design.

• Essentially it's a movement of money from an Account to another.
• Movement of quantity can be expressed as AccountingEvent and Entry
• Movement is not always single entry. AccountingTransaction supports multi-legged entries.
• The movement is governed by Agreements and PostingRules.
• There are 3 patterns of adjustment. A general rule is
  1. Cancel(Replace) -- use ReplaceAdjustment to remove the original transaction, and add a new one as necessary. This is possible when the original transaction (event) has no subsequent events. It's practical but not GAAP compliant.
  2. Reverse -- add entries with negated amount. This is the most common case that keeps both of the erratic and correct entries.
  3. Adjust difference -- use DifferenceAdjustment when the original transaction is already closed, and you need to create a new entry for the adjustment.

See tests/electricity.py and tests/test_electricity.py

• Remove Java-ism.
• Create general purpose accouting mixin that supports any quantifiable.

• The main article http://martinfowler.com/apsupp/accounting.pdf

• Account http://martinfowler.com/eaaDev/Account.html

• Accounting Entry http://martinfowler.com/eaaDev/AccountingEntry.html

• Service Agreement and Posting Rule http://martinfowler.com/eaaDev/AgreementDispatcher.html

• Reversal Adjustment http://martinfowler.com/eaaDev/ReversalAdjustment.html

• Replacement Adjustment http://martinfowler.com/eaaDev/ReplacementAdjustment.html

• Difference Adjustment http://martinfowler.com/eaaDev/DifferenceAdjustment.html