Rcmd Check: Unexported objects imported by '::

问题:

This question is related to Rcmd check in R-Devel (3.1.0).

I am maintaining a package, call it A, that "Depends" on another package, let me call this second package B. I have used "Depends" instead of "import" for the following reasons:

• most people using package A also use package B.
• package A extensively use function from package B.
• package B, itself, "depends" on other packages.

Package A make use of "unexported" function of package B and Rcmd check complaints about the following: Unexported objects imported by ':::' calls (as a NOTE, but I want to remove all of them). My question is: how should I properly handle this note? How should I properly make use of "unexported" function from another package?

I know that we should not use "unexported" function, but I am involved in the development of both packages.