future() arguments for passing R options and environment variables

[HenrikBengtsson]

There are cases where one needs to customize options and environment variables used by the future. This can be done by explicitly setting those in the future expression, but that might be tedious, especially to make sure that they are unset afterward. Having future() do it for us is easier and avoids some code clutter. Here's one idea:

# Set env var 'FOO' with its currently set value, if set + set 'BAR' to "42"
f <- future(..., envvars = c("FOO", BAR = "42"))

# Set R options 'foo' with its currently set value, if set + set 'bar' to 42L
f <- future(..., options = c("foo", BAR = 42L))

These arguments should be exposed also in map-reduce APIs, e.g. future.apply and furrr.

Possible concerns

• All types of options and environment variables should not be exported; is that something that future should monitor/protect again?
• In R, certain environment variables must be set before launching R; is that something that future should monitor/protect again?

[yogat3ch]

[...]

Are there any workarounds you are aware of @HenrikBengtsson that we can use until this feature is added?

[...]

[HenrikBengtsson]

Are there any workarounds you are aware of @HenrikBengtsson that we can use until this feature is added?

The workaround would be to set the option or the environment variable manually inside the future where the values are passed via globals, e.g.

myenv <- Sys.getenv("MYENV")
myopt <- getOption("myopt")
f <- future({
  Sys.setenv(MYENV = myenv)
  options(myopt = myopt)
  ...
})

[yogat3ch]

Hi @HenrikBengtsson,
This doesn't work for functions because they retain the namespace that they were loaded in as the function environment, which is not available in the background process.

[...]

[HenrikBengtsson]

This doesn't work for functions because ...

Okay, so that sounds like a different problem than what this issue is about ("passing R options and environment variables"). Can you please bring this up on https://github.com/HenrikBengtsson/future/discussions instead.

[yogat3ch]

Sure, will do.

[yogat3ch]

Continued in #552