Thanks for pointing this out. The commit you cite was reverted a couple
days later, because we are still thinking about how it should work. While
it appears Date would benefit, weird things happen e.g. with POSIXlt and
other data structures in the wild. This is due to inconsistency in the
behaviors
Regarding, this news item for r-devel:
‘for()’ loops are generalized to iterate over any object with ‘[[’ and
‘length()’ methods. Thanks to Hervé Pagès for the idea and the patch.
Below dd is an object for which [[ and length work but the result is
still numeric rather than Date class in "R Unde
