Add a ctor() helper, to reduce boilerplate

Hello @majelbstoat, 

Please review the following commits I made in branch 'nick-ctor'.

6e08add66042d1ffd4f131ccec79208c34c467e6 (2014-03-06 15:13:52 -0500)
Add a ctor() helper, to reduce boilerplate

R=@majelbstoat