Shopify/batman — Issue #247: Batman should support polymorphic associations
Author: hornairs
Created: 2011-11-23 23:12:00+00:00
State: open
Labels: Feature

A good example would be [Events](http://api.shopify.com/event.html) in the Shopify API, which have both a `subject_id` and a `subject_type`.

My first thought is to just do a compound `SetIndex`?