odoo/odoo — pull request #1468 by pedrobaeza (2014-07-31 07:14:32+00:00)
Title: 8.0 purchase line hooks

With these hooks, modules like _purchase_discount_ (https://github.com/OCA/purchase-workflow/tree/master/purchase_discount) don't have to make dirty patches to extend functionality, and also other possibilities, like 3x2 offers, can be made in a clean way.