[R-pkg-devel] Do I need to namespace and import functions from 'methods' package?

I have a package that is using the 'is' function from the 'methods'
package.  My package has been on CRAN for some time now and has had 3
different versions already. Yesterday when submitting, I got a response
with:

* checking R code for possible problems ... NOTE

ggMarginal: no visible global function definition for 'is'
Undefined global functions or variables:
  is

So I fixed it by changing 'is' to 'methods::is', and then I got a response

* checking dependencies in R code ... WARNING

'::' or ':::' import not declared from: ?methods?

So I suppose I need to declare 'methods' in my imported packages.

My question is: is this a new requirement, to explicitly import 'methods'
and namespace functions from it, or has it always been a requirement but I
just wasn't caught? Or is it not even a requirement and the R CMD check was
being weird?

Yes, this is expected.  See:
http://developer.r-project.org/blosxom.cgi/R-devel/NEWS/2015/06/29#n2015-06-29

And an earlier email on this list:
https://stat.ethz.ch/pipermail/r-package-devel/2015q2/000171.html

On 12/07/2015 4:01 PM, Dean Attali wrote:

I have a package that is using the 'is' function from the 'methods'
package.  My package has been on CRAN for some time now and has had 3
different versions already. Yesterday when submitting, I got a response
with:

* checking R code for possible problems ... NOTE

ggMarginal: no visible global function definition for 'is'
Undefined global functions or variables:
  is

So I fixed it by changing 'is' to 'methods::is', and then I got a

response

* checking dependencies in R code ... WARNING

'::' or ':::' import not declared from: ?methods?

So I suppose I need to declare 'methods' in my imported packages.

My question is: is this a new requirement, to explicitly import 'methods'
and namespace functions from it, or has it always been a requirement but

I

just wasn't caught? Or is it not even a requirement and the R CMD check

was

being weird?

It is a new requirement.  As Joshua Ulrich posted on Friday,

Yes, this is expected.  See:

http://developer.r-project.org/blosxom.cgi/R-devel/NEWS/2015/06/29#n2015-06-29

And an earlier email on this list:
https://stat.ethz.ch/pipermail/r-package-devel/2015q2/000171.html