I propose that loadings() be made generic in R-devel with definition
loadings <- function(x, ...) UseMethod("loadings")
loadings.default <- function(x, ...) x$loadings
The default is the current definition of loadings with the ... argument
added.
The current definition is not specific about the returned value, though
$loadings may usually be a matrix. I'm not sure what would be broken if
a more strict definition of the return value is enforced. For my
purposes a matrix is fine, but I am not sure that there is a benefit
from imposing that the returned value must be a matrix, so I suggest
sticking with the current non-specific structure for the return value.
(For piecewise linear or other non-linear analysis there may be good
reasons to allow more general structures for the loadings.)
Paul Gilbert