printing variables in console while debugging

[asiripanich]

Hi @wahani, first of all thank you for making this great package.

Could you point out to why printing variables such has a data.frame or a list is not possible when I'm debugging inside a script imported with modules. I haven't done a lot of digging on this but hoping you can give me an answer to why this is not a default behaviour of modules.

Cheers.

[wahani]

Hi, thanks for reporting the issue!

I don't see a reason for this behaviour and it shouldn't be that way. Can you give a minimal example so I can degug it?

[asiripanich]

I guess it was because I was trying to debug inside furrr::future_map.

 library(modules)

  m <- modules::module({
    modules::export("add_one")
    add_one = function(x) {
      browser()
      x + 1
    }
  })

  # can print x in console while in debugging mode
  m$add_one(x = 1)

  library(future)
  library(furrr)
  future::plan(future::sequential)

  # cannot print x in console while in debugging mode
  furrr::future_map(.x = 1, 
                    .f = ~ m$add_one(.x))

Session info:

R version 3.6.1 (2019-07-05)
Platform: x86_64-apple-darwin15.6.0 (64-bit)
Running under: macOS Mojave 10.14.6

Matrix products: default
BLAS:   /System/Library/Frameworks/Accelerate.framework/Versions/A/Frameworks/vecLib.framework/Versions/A/libBLAS.dylib
LAPACK: /Library/Frameworks/R.framework/Versions/3.6/Resources/lib/libRlapack.dylib

locale:
[1] en_AU.UTF-8/en_AU.UTF-8/en_AU.UTF-8/C/en_AU.UTF-8/en_AU.UTF-8

attached base packages:
[1] stats     graphics  grDevices utils     datasets  methods   base     

other attached packages:
[1] purrr_0.3.3        furrr_0.1.0        future_1.16.0     
[4] modules_0.8.0      usethis_1.5.1.9000 colorout_1.2-2    

loaded via a namespace (and not attached):
 [1] Rcpp_1.0.3       codetools_0.2-16 listenv_0.8.0    digest_0.6.24   
 [5] magrittr_1.5     rlang_0.4.4      fs_1.3.1         tools_3.6.1     
 [9] glue_1.3.1       parallel_3.6.1   compiler_3.6.1   globals_0.12.5  

[wahani]

@asiripanich Thanks for the example. I can reproduce the behavior. However it may be related to furrr::future_map and not to modules. I tested the following:

modules::depend("future")
modules::depend("furrr")
future::plan(future::sequential)

add_one <- function(x) {
  browser()
  x + 1
}

# cannot print x in console while in debugging mode
furrr::future_map(
  .x = 1, 
  .f = ~ add_one(.x)
  )

and observe the same. Can you verify? Printing from the function is no problem,regardless of whether it is in a module, it is only in debug.

I only have experience with the parallel package and must say, that with parallel and asynchronous execution it's good to have a debugger at all ;) With parallel I would have to go into lapply for debugging.

[asiripanich]

@wahani I tried the above and can confirm the same behaviour. I guess I should seek help from other places. Maybe furrr? :) Thanks again for helping me to investigate this. Great package by the way!