[R] source files in temp environment

[Duncan Murdoch]

On 02/12/2017 5:48 AM, Alexander Shenkin wrote:
> Hi all,
> 
> I often keep code in separate files for organizational purposes, and
> source() that code from higher level scripts.  One problem is that those
> sourced files often create temporary variables that I don't want to keep
> around.  I could clean up after myself with lots of rm()'s, but that's a
> pain, and is messy.
> 
> I'm wondering if one solution might be to source the code in a temporary
> environment, assign outputs of interest to the .GlobalEnv with <<-, and
> then delete the environment afterwards.  One way to do this:
> 
> file.r:
> temp1 = 1
> temp2 = 2
> desired_var <<- temp1 + temp2
> 
> console:
> temp_e = new.env()
> source("file.r", local = temp_e)
> rm(temp_e)
> 
> It's a bit messy to create and delete environments, so I tried what
> others have referred to:
> 
> source("file.r", local = attach(NULL))
> 
> This, however, results in a persistent "NULL" environment in the search
> path.
> 
>   > search()
> ".GlobalEnv"            "package:bindrcpp"      "NULL"
> "tools:rstudio"         "package:stats"         "package:graphics"
> "package:grDevices"     "package:utils"         "package:datasets"
> "package:methods"       "Autoloads"             "package:base"
> 
> Of course, functions are built to encapsulate like this (and do so in
> their own temporary environment), but in many cases, turning the sourced
> code into functions is possible but clunky.
> 
> Any thoughts or suggestions would be much appreciated.

I would wrap the calls in the local() function, or put them in a 
function and call that.  That is,

local({
   source("file.R", local = TRUE)
})

or

sourceit <- function() {
   source("file.R", local = TRUE)
}
sourceit()

With respect to your last comment (turning the code in file.R into 
functions which don't leave their locals behind):  I think that would be 
the best solution.  You may find it clunky now, but in the long run it 
likely will help you to make better code.

Duncan Murdoch