lazy

The lazy package provides the tools necessary to do non-stadard evaluation "right" in R. There are three principles:

Instead of using substitute(), use lazy() to capture both expression and environment.
Every function that uses NSE should have a standard evaluation partner that does all the work. This function should end with _.
The SE-partner has a flexible input specification to make it easy for people to program with.

See the vignette for more details.

To install:

devtools::install_github("hadley/lazy")