[R] source files in temp environment

[Eric Berger]

I totally agree with Duncan's last point. I find it hard to reconcile your
early remarks (which indicate a deep knowledge of programming) with the
idea that your code is not built up from combining small(ish) functions.
Small functions would generally be considered best practices. Try searching
on this topic to see discussions and pointers.

On Sat, Dec 2, 2017 at 1:01 PM, Duncan Murdoch <murdoch.duncan at gmail.com>
wrote:

> 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
>
>
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