[SOLVED] I get an error when using {future} and {furrr} functions within a Golem Shiny App, what does it come from?

I get an error when using {future} and {furrr} functions within a Golem Shiny App, what does it come from?

I am currently working on a Golem Shiny App called "package_name" (which is a requirement for me) for which some functions I created need to use functions from the {furrr} and {future} packages. However, whenever I try to run them, I get the following error :

Error : there is no package called 'package_name'

Please note that whenever any function that does not use either package works perfectly fine.

Does anyone know what the problem might be ?

Thanks !

Solution

While building the application with {golem}, the package with the app is not installed on your machine. When you use {future}, the code is run inside another R session, meaning that the objects are transported and the libraries reloaded.

BUT if you try to use a function from inside your current app into your future, you need to make it "transportable", and using package_name::function() will not work because your package is not installed.

Let's say you need to use current_app_fun(), defined inside your package. Technically, {future} will be able to transport this function, as it uses {globals} to identify the objects to transport to the new R session.

observeEvent( input$bla , {
  # future() will identify that it needs to
  # transport current_app_fun()
  future({
    current_app_fun()
  })
})

You can also do an extra step just to be extra cautious:

observeEvent( input$bla , {
  func_for_future <- current_app_fun
  future({
    func_for_future()
  })
})

Cheers, Colin