Allow for python-like `if ("__main__")` pattern

[jtlandis]

Please describe your feature request

I have found box as a useful package and I was curious if we could implement a function that would allow for certain R scripts to either run as an R script, or import exported functionality into another with box::use.

Since R doesn't have a mangling system like python, I imagine it would look something like

#' @export
execute_function <- function(...) {
 # ...
}

# only execute function if Rscript is called by command line
# otherwise, just make it available for module
if (is_rscript_exec(file_pattern = "My_script_name.R")) {
  execute_function(...)
}

[klmr]

That’s already implemented: box::name() corresponds to the current module name. You can use it as follows:

if (is.null(box::name())) {
    # only executed if the code is invoked as a script.
}