Tab autocomplete in positron for argument names doesn't seem to work?

[njtierney]

In RStudio, I'm used to being able to start typing a function out, and then pressing tab to get a list of possible arguments - here's a screenshot:

However, in Positron, I don't seem to be able to do this:

I get autocomplete help when I already know the function name, but I want a bit more help than that.

I feel like I probably just need to turn on some feature of positron, however this has been a bit of a stumbling block for me - I didn't realise how much I relied on tab-autocomplete!

Any help would be much appreciated.

I'm currently using the latest downloaded release of positron:

Positron Version: 2025.07.0 (Universal) build 74
Code - OSS Version: 1.100.0
Commit: fe621e856f2e66144c97d30a3c77471947048e61
Date: 2025-06-09T03:37:56.615Z
Electron: 34.5.1
Chromium: 132.0.6834.210
Node.js: 20.19.0
V8: 13.2.152.41-electron.0
OS: Darwin arm64 23.5.0

[juliasilge]

So are you saying you see the arguments in the hover help, but you don't have them as completions? Can you try a few things for me:

• Type rnorm() and put your cursor between the parentheses, then hit Tab. Are those completions what you are expecting?
• Type out rnorm with parentheses on separate lines like you show in your screenshots and then try bringing up completion with the other keyboard shortcut, Ctrl+Space. Are those the completions you were expecting?

I think we may need to navigate/adjust how Tab acts in the multiline statement situation.

[juliasilge]

Related to #4396

[ateucher]

I was chatting to Nick about this, thought I'd give it a try:

• Type rnorm() and put your cursor between the parentheses, then hit Tab. Are those completions what you are expecting?

Yes, this works as expected (selectable list of arguments for completions pops up)

• Type out rnorm with parentheses on separate lines like you show in your screenshots and then try bringing up completion with the other keyboard shortcut, Ctrl+Space. Are those the completions you were expecting?

This didn't work at first, until I removed the macOS keyboard shortcut that used Ctrl+Space to switch input sources:
.

After I deselected that and restarted Positron, Ctrl+Space brings up the completions menu when the cursor is on a new line between parentheses

[njtierney]

Type rnorm() and put your cursor between the parentheses, then hit Tab. Are those completions what you are expecting?

For me it just lists the arguments in a popup, it doesn't provide the ability to choose them like in Rstudio:

positron:

Rstudio:

Type out rnorm with parentheses on separate lines like you show in your screenshots and then try bringing up completion with the other keyboard shortcut, Ctrl+Space. Are those the completions you were expecting?

Yes this is the sort of completion I would like!

Is there a way for me to map this to Tab, somehow?

[jennybc]

@njtierney I am surprised that hitting tab when you have rnorm(@) (where @ indicates cursor position) does not give argument completions. It does for me. I feel like you must have some configuration that's part of the picture here (?).

[njtierney]

That is entirely possible, @jennybc - is there a preferred way to share my config/keybindings? Here is my keybindings.json file:

// Place your key bindings in this file to override the defaults
[
    {
        "key": "Ctrl+Cmd+C",
        "command": "workbench.action.executeCode.console",
        "when": "editorTextFocus",
        "args": {
            "langId": "r",
            "code": "chores::.init_addin()",
            "focus": true
        }
    },
    {
        "key": "Cmd+Shift+R",
        "command": "workbench.action.executeCode.console",
        "when": "editorTextFocus",
        "args": {
            "langId": "r",
            "code": "reprex::reprex_selection()",
            "focus": true
        }
    },
    {
        "key": "shift+cmd+2",
        "command": "workbench.action.terminal.focus",
        "when": "terminalHasBeenCreated || terminalProcessSupported"
    }
] 

[DavisVaughan]

A few things worth keeping in mind:

• You must set an RStudio setting to opt in to the multiline tab for autocompletion behavior, see Support autocomplete for R across multiple lines #4396 (comment)
• The reason it is opt in in RStudio is because there is an ambiguity there. Did you really want a \t character? Or did you want autocompletions? It's rather hard to get it right 100% of the time, and if you are wrong and always guess autocompletions, it's frustrating when you actually want to insert a tab but can't. The alternative way to bring up completions is Ctrl+Space, which does not have this ambiguity, so it works "anywhere", including when you're spanning multiple lines as you noticed above.

I'm not saying we shouldn't provide some support for this, but I am saying we probably should not do it by default, due to the ambiguity which has frustrated me in the past.

[njtierney]

Thanks for this, @DavisVaughan

A few things worth keeping in mind:

• You must set an RStudio setting to opt in to the multiline tab for autocompletion behavior, see Support autocomplete for R across multiple lines #4396 (comment)

Yes, and I have this setting turned on - I guess my point is that this feature doesn't seem to exist (as far as I can see?) in Positron. I think having it opt-in makes total sense!

• The reason it is opt in in RStudio is because there is an ambiguity there. Did you really want a \t character? Or did you want autocompletions? It's rather hard to get it right 100% of the time, and if you are wrong and always guess autocompletions, it's frustrating when you actually want to insert a tab but can't. The alternative way to bring up completions is Ctrl+Space, which does not have this ambiguity, so it works "anywhere", including when you're spanning multiple lines as you noticed above.

I'm not saying we shouldn't provide some support for this, but I am saying we probably should not do it by default, due to the ambiguity which has frustrated me in the past.

Totally agree that this should not be on by default, but it is a feature I have some to use extensively, especially since I don't really use tab for anything else now, especially because of the wonderful auto-save code style of air! To me, pressing tab is me asking "what are my options" - and while it is good to have Ctrl+Space as an alternative, I would really appreciate having tab autocomplete.