"global parameter" warning using data.table in package.

Hi,

  I am converting a couple of functions into a R-package. Many of the
functions use data.table.
  I have two questions using data.table in my own package.
  Normally I would put each question in separate emails but I think they
might be connected.

First question is short and I think the answer is yes.
1. Do I always need to prefix data.table each time I use something from
that package?
Eg. DT <- data.table::data.table(x=rep(c("b","a","c"),each=3), y=c(1,3,6),
v=1:9)

Second question is longer.
2.  In this small example code:
hello <- function() {
  DT <- data.table::data.table(x=rep(c("b","a","c"),each=3), y=c(1,3,6),
v=1:9)
  DT[, .(sum(v))]
}

I get these warnings from R CMD check:
hello: no visible global function definition for ?.?
hello: no visible binding for global variable ?v?
Undefined global functions or variables:
  . v

According to: vignette("datatable-importing", package = "data.table")
The solution is
hello <- function() {
  v <- NULL
  . <- NULL

And it works but looks a bit weird.
Is there a better solution?

Regards
Martin