Reset non-set environment variables about callr HOT 9 CLOSED

That would be very fragile, as it is not clean what versions of what platforms need which env vars.

It would also be a breaking change, as existing code might rely on the inheritance of environment variables.

Nevertheless, if you want to do that, you can, by setting (nearly?) all existing env vars to NA.

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So if one wants to do that manually, they just wrap callr with a variant of the set(temporary); callr(...); set(previous) dance?

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No, you can use the env argument:

❯ Sys.setenv("FOO" = "bar")

❯ callr::r(function() Sys.getenv("FOO"))
[1] "bar"

❯ callr::r(function() Sys.getenv("FOO"), env = c(FOO = NA_character_))
[1] ""

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Ah. No, I meant to implement the logic I hinted at in the first post.

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Yes, if you want to start with a clean environment, set all current env vars to NA in the env argument.

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I guess since both Sys.unsetenv and callr's env parameter require explicit listing of the existing variables to "unset" it is only a question of API stability.

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No, do not use Sys.unsetenv(), that's not a good solution. R is single threaded, but occasionally there is a async code execution, e.g. finalizers might be triggered by the garbage collector, and they may use env vars.

Plus, callr's machinery might use env vars as well, so if you unset them before calling callr, then you might change callr's behavior.

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Good point!

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A better solution to reset the environment for the subprocess is to exploit a platform-dependent solution like env -i then.

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