How to use names from a different package inside a module?

[EKtheSage]

Error description

Hi,

I just started learning about box, so I may not know the right way to use it yet. I ran into this error the other day, hopefully you can show me how to do it.

I wrote a test function in test.R script in the R folder in my project

test <- function(dat) {
  dat %>% 
    filter(x == 3)
  
  dat
}

In a separate file, I called the function using box:

box::use(
  R/test[test],
  dplyr[...]
)

In search() I can see both dplyr and test.R in the environment:

> search()
 [1] ".GlobalEnv"        "mod:dplyr"         "mod:R/test"        "tools:rstudio"     "package:stats"    
 [6] "package:graphics"  "package:grDevices" "package:utils"     "package:datasets"  "package:methods"  
[11] "Autoloads"         "org:r-lib"         "package:base"     

But if I call test(mtcars) it resulted in the following error:

> test(mtcars)
Error in dat %>% filter(x == 3) : could not find function "%>%"

R version

> R.version
               _                           
platform       x86_64-w64-mingw32          
arch           x86_64                      
os             mingw32                     
system         x86_64, mingw32             
status                                     
major          4                           
minor          1.2                         
year           2021                        
month          11                          
day            01                          
svn rev        81115                       
language       R                           
version.string R version 4.1.2 (2021-11-01)
nickname       Bird Hippie

‘box’ version

1.1.2

[klmr]

With ‘box’, the contents of different modules are strictly isolated from each other.

So if you have a module test.R that needs the %>% operator or the filter function (or any other function), you need to import those names inside that module. You can’t put the code for the import into a separate file.

In your case, this means that you need to move the relevant box::use() declaration into test.R:

box::use(dplyr[...])

test <- function(dat) {
  dat %>% 
    filter(x == 3)
}

(Note that I also removed the last line of your test function, since you returned the unmodified dat, which was probably not intended.)

And in your other code that uses test.R, you no longer need to import ‘dplyr’ (unless you’re using it there, as well):

box::use(R/test[test])

[lo-zed]

Hi @klmr , first of all, thanks for this package, I really like the idea.
I had the same question regarding base packages: is it normal that for example utils::head isn't reachable either?

[mrismailt]

@lo-zed {box} doesn't load any functions or packages by default. If you would like to use utils::head from within a {box} module, you can either load the entire {utils} package

box::use(utils[...])

Or just the head function from {utils}

box::use(utils[head])

[lo-zed]

alright, thank you very much for your answer. I'd have thought it would be different with base packages.

[klmr]

@lo-zed There’s an ambiguity in R between the specific package called ‘base’, and the core R packages (including ‘base’, ‘stats’, ‘utils’, etc.), which are often also referred to as “base R”. To avoid this ambiguity I generally refer to these packages as “core R” instead. And in fact, as @mrismailt wrote, ‘box’ modules do not load/attach any packages (including core R packages) by default, except for the specific package ‘base’ (because without that package you can’t do anything in R).

This behaviour is in fact very similar to how R packages behave: inside the code of R packages, if you want to use head, you should also declare a ‘utils’ import, otherwise R CMD check will complain (though the code will still work without that declaration).

However, since users frequently want to have all the core R packages loaded, ‘box’ offers a way to load all of them at once without having to load them individually:

box::use(r/core)
# or, attaching all names:
box::use(r/core[...])

Please refer to this FAQ entry for details.

[lo-zed]

ok great, thanks a lot. I had missed the FAQ, thanks for pointing it to me too.