BUG: $ method for dframes returns single NA

[clarkfitzg]

> a = as.dframe(iris)
> colnames(a)
[1] "Sepal.Length" "Sepal.Width"  "Petal.Length" "Petal.Width"  "Species"
> a$Species
Species
   <NA>
Levels: setosa versicolor virginica
> iris$Species
  [1] setosa     setosa     setosa     setosa     setosa     setosa
  [7] setosa     setosa     setosa     setosa     setosa     setosa
 [13] setosa     setosa     setosa     setosa     setosa     setosa

Probably the best way to fix this is to include dframes in OO model as described in the design section of the wiki.