Set `.Platform$GUI` to "Positron" in console sessions only #977

juliasilge · 2025-12-02T22:14:27Z

With this change, I see results like this in the Positron console:

> .Platform
$OS.type
[1] "unix"

$file.sep
[1] "/"

$dynlib.ext
[1] ".so"

$GUI
[1] "Positron"

$endian
[1] "little"

$pkgType
[1] "mac.binary.big-sur-arm64"

$path.sep
[1] ":"

$r_arch
[1] ""

And results like this in an R session running in an integrated terminal in Positron (the same as RStudio):

> .Platform
$OS.type
[1] "unix"

$file.sep
[1] "/"

$dynlib.ext
[1] ".so"

$GUI
[1] "X11"

$endian
[1] "little"

$pkgType
[1] "mac.binary.big-sur-arm64"

$path.sep
[1] ":"

$r_arch
[1] ""

Does SessionMode::Console really just mean only in Positron? Is there some better way for ark to know when it's running in Positron at initialization?

juliasilge · 2025-12-02T22:21:19Z

crates/ark/src/interface.rs

+            // Set .Platform$GUI to "Positron" for console sessions only
+            if session_mode == SessionMode::Console {
+                let result = harp::parse_eval_global(r#"
+                    unlockBinding(".Platform", baseenv())
+                    .Platform$GUI <- "Positron"
+                    lockBinding(".Platform", baseenv())
+                "#);
+                match result {
+                    Ok(_) => log::info!("Set .Platform$GUI to 'Positron' for console session"),
+                    Err(err) => log::warn!("Failed to set .Platform$GUI: {err:?}"),
+                }
+            }
+


I'm not sure what the best approach is, but this one is at least easy to reason about.

Some other approaches I tried out included:

Do something like r_symbol!(".Platform") in Rust and find the GUI element. I like that this doesn't involve executing R code during some initialization step, but you still have to lock/unlock (just at the C level).

Do the locking/unlocking in startup.R. This feels like a better place to run such R code, but I'm not sure we can check session mode there and the other options there are more user-facing.

RStudio does it here, which is not exactly the same but similar in that in happens post-initialization:
https://github.com/rstudio/rstudio/blob/5381a9a4363eae00007fd170302fa8a5c93050b5/src/cpp/r/R/Options.R#L126

I think I'd prefer this to be in an R file, maybe in modules/positron/positron.R. Then you can use:

.Platform <- base::.Platform .Platform$GUI <- "Positron" env_bind_force(baseenv(), ".Platform", .Platform)

lionel-

We probably need to set GUI to something else than "Positron" when Ark runs with another frontend. To determine that, we could detect whether Sys.getenv("POSITRON_VERSION") is defined. If not, we'd set GUI to "Ark". What do you think?

lionel- · 2025-12-03T08:06:46Z

crates/ark/src/interface.rs

+            // Set .Platform$GUI to "Positron" for console sessions only
+            if session_mode == SessionMode::Console {
+                let result = harp::parse_eval_global(r#"
+                    unlockBinding(".Platform", baseenv())
+                    .Platform$GUI <- "Positron"
+                    lockBinding(".Platform", baseenv())
+                "#);
+                match result {
+                    Ok(_) => log::info!("Set .Platform$GUI to 'Positron' for console session"),
+                    Err(err) => log::warn!("Failed to set .Platform$GUI: {err:?}"),
+                }
+            }
+


I think I'd prefer this to be in an R file, maybe in modules/positron/positron.R. Then you can use:

.Platform <- base::.Platform .Platform$GUI <- "Positron" env_bind_force(baseenv(), ".Platform", .Platform)

juliasilge · 2025-12-03T15:35:23Z

Ah, I am experimenting and it looks like the .R files in modules/positron/ are only evaluated in the Positron console? Not R sessions in integrated terminals? That will work well then.

This reverts commit b78ba94.

This reverts commit e5ae05b.

juliasilge · 2025-12-03T16:28:08Z

This is a much better approach. Thanks, @lionel-!

lionel- · 2025-12-03T16:35:37Z

crates/ark/src/modules/positron/positron.R

+.Platform <- base::.Platform
+.Platform$GUI <- "Positron"


Can we make it "Ark" if Sys.getenv("POSITRON") is not set? Or leave the default.

Just so I understand, files in modules/positron get evaluated outside of Positron? All the options in options.R, etc? Can you explain a bit more about this?

I think #588 is about this.

Just so I understand, files in modules/positron get evaluated outside of Positron? All the options in options.R, etc? Can you explain a bit more about this?

They do because some of the files in there provide essential Ark functionality, for instance regarding error handling.

Maybe the folder really should be called ark? Or maybe we should split ark from the positron folder and the latter would only get sourced in Positron? That would be a nice way to easily differentiate generic and positron-specific functionality.

We could then have a .ark. prefix in addition to the .ps. prefix, for symbols exported from the ark folder.

I went ahead and checked the env var in 1b11568, ahead of improvements like that.

crates/ark/src/modules/positron/positron.R

Co-authored-by: Lionel Henry <lionel.hry@proton.me>

Set .Platform$GUI to "Positron" in console sessions only

e5ae05b

juliasilge commented Dec 2, 2025

View reviewed changes

Add simple test

b78ba94

juliasilge requested a review from lionel- December 3, 2025 01:16

lionel- reviewed Dec 3, 2025

View reviewed changes

juliasilge added 3 commits December 3, 2025 08:42

Revert "Add simple test"

1844fa4

This reverts commit b78ba94.

Revert "Set .Platform$GUI to "Positron" in console sessions only"

baa731d

This reverts commit e5ae05b.

Set .Platform$GUI just in the positron module

0b46409

juliasilge requested a review from lionel- December 3, 2025 16:28

lionel- reviewed Dec 3, 2025

View reviewed changes

This all gets evaluated outside of Positron as well

1b11568

juliasilge requested a review from lionel- December 3, 2025 17:22

lionel- approved these changes Dec 3, 2025

View reviewed changes

crates/ark/src/modules/positron/positron.R Outdated Show resolved Hide resolved

Update crates/ark/src/modules/positron/positron.R

9164458

Co-authored-by: Lionel Henry <lionel.hry@proton.me>

juliasilge merged commit 401cf71 into main Dec 3, 2025
8 checks passed

juliasilge deleted the platform-gui-console-positron branch December 3, 2025 18:19

github-actions bot locked and limited conversation to collaborators Dec 3, 2025

Set .Platform$GUI to "Positron" in console sessions only #977

Set .Platform$GUI to "Positron" in console sessions only #977

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Set `.Platform$GUI` to "Positron" in console sessions only #977

Set `.Platform$GUI` to "Positron" in console sessions only #977

lionel- Dec 3, 2025 •

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