Inverted to negative screen on OSX

Great for presentation when ambient lights are too bright and words can't be seen.

CTRL+OPT+CMD+8


etc hosts on OSX


sudo vi /private/etc/hosts
or
sudo vi /etc/hosts


Rspec validate_presence_of matcher with scope

it { should validate_uniqueness_of(:foo).scoped_to(:bar) }

Ruby case switch gotcha

Doh. Ruby's case switch implicitly checks Object#class.

http://www.postal-code.com/mrhappy/blog/2007/02/01/ruby-comparing-an-objects-class-in-a-case-statement/