By accident, I just realized that an ActiveRecord date field can be set
using a third way...
foo = Fo.new
foo.start_date = Date.new(2016, 1, 31)
foo.start_date = '2016-01-31'
and to my surprise...
foo.start_date = '31/1/2016'
Where can I find documentation on this? I've searched to the point of
wasting my time.