Import advice generates unfortunate NOTE in R CMD check

[vspinu]

From namespace/import-r:

If you are using just a few functions from another package, my recommendation is to note the package name in the Imports: field of the DESCRIPTION file and call the function(s) explicitly using ::, e.g., pkg::fun().

This generates CMD check note Namespace in Imports field not imported from .... For example in the current lubridate:

* checking dependencies in R code ... NOTE
Namespace in Imports field not imported from: ‘memoise’
  All declared Imports should be used.

To silence this note one would need to use @importFrom pkg func at least once in the package.

[hadley]

That's because you've created a build-time dependency not a run time dependency. (Use it in a function to see why)

I'm not sure what the best solution is. This action is fundmentally dangerous because it uses the memorise package that you have installed when running R CMD build, not the package loaded when the user loads your package

[vspinu]

That's because you've created a build-time dependency not a run time dependency.

Yeh. That's indeed the reason for it. Thanks.

I'm not sure what the best solution is.

I can think of two solutions. Either to use an unlocked environment inside the package to hold the function or implement a simple caching mechanism inside this function and abandon memoise dependency.. As memoise is used only once in the package I will probably go with the second.

---

Any ideas about where the other NOTE comes from?

* checking dependencies in R code ... NOTE
Package in Depends field not imported from: ‘methods’
  These packages need to be imported from (in the NAMESPACE file)
  for when this namespace is loaded but not attached.

I don't see the point of this message;methods is always attached.

It seems to be a common issue with methods which some people fix by importing the whole method package. An outrageous solution as all exported functions from methods are effectively copied into each of such packages.

[hadley]

Methods is not attached when you use Rscript (ridiculous but true). Importing the whole package is fine (if a bit inelegant) - the copies are just pointers, not deep. You can just important individual methods of you want to avoid that.

[vspinu]

Methods is not attached when you use Rscript (ridiculous but true).

Aha!

Importing the whole package is fine (if a bit inelegant) - the copies are just pointers, not deep. You can just important individual methods of you want to avoid that.

Yeh. I did the latter. Thanks.