positional-arguments does not work with set shell?

[Cologler]

For

set positional-arguments

run args:
    @echo $@

Execute just run 2023 print:

2023

---

For

set positional-arguments
set shell := ["pwsh", "-c"]

run args:
    @echo $@

Execute just run 2023 print:

$@
run
2023

---

For

set positional-arguments
set shell := ["nu", "-c"]

run args:
    @echo $@

Execute just run 2023 print:

Error: nu::parser::variable_not_found (link)

  × Variable not found.
   ╭─[source:1:1]
 1 │ echo $@
   ·      ─┬
   ·       ╰── variable not found
   ╰────

error: Recipe `run` failed on line 5 with exit code 1

Test on just 1.13.0.

[runeimp]

This seems to be a duplicate of #1554

But also Error: nu::parser::variable_not_found (link) looks like Nu shell instead PowerShell. Is your default shell Nu? If so this might be another part of the same issue of simply using set positional-arguments with PowerShell Core. What operating system are you using?

[Cologler]

This seems to be a duplicate of #1554

But also Error: nu::parser::variable_not_found (link) looks like Nu shell instead PowerShell. Is your default shell Nu? If so this might be another part of the same issue of simply using set positional-arguments with PowerShell Core. What operating system are you using?

My mistake. I updated the last example.

The arguments should expand by just.exe, whatever my default shell and OS are.

[runeimp]

Thanks for the clarification. So the pwsh example is definitely the same as I was experiencing in #1554. Nu shell is similar to PowerShell in that they are both object based shells instead of string based like the majority of other shells in existence. So might have something to do with a possible change in Just v1.13.0. As this was not an issue I'd seen prior using Just with PowerShell. Though it may have existed prior and I simply hadn't tried using set positional-arguments with PowerShell before. I seem to remember a little oddness with Nu shell but It's been a while since I played with that Shell and Just. Any thoughts @casey ?

[cspotcode]

Pretty sure nu does not allow access to positionals via $@, $args, et al, you have to wrap your script in a function declaration: https://www.nushell.sh/book/scripts.html#parameterizing-scripts

[runeimp]

@cspotcode As I understand it using set positional-arguments is an enhancement that preprocesses the $@, $1, $2, etc. tokens before handoff to the the shell. If set positional-arguments was not enabled then those tokens would absolutely have to be handled by the shell itself.

[cspotcode]

No, set positional-arguments appends them to the argv array when invoking the shell, it doesn't do any preprocessing.

My writeup in #1592 goes into greater detail.

But you can experiment with the following justfile to understand the exact argv array that is being received by the target executable.

# Try running `just default hello world` and carefully inspect the output
set shell := ["python", "-c", "import sys; print(sys.argv)"]
set positional-arguments
default *args:
    foo bar baz "$@" "$1"

$ just default hello world
foo bar baz "$@" "$1"
['-c', 'foo bar baz "$@" "$1"', 'default', 'hello', 'world']

This proves that just is not preprocessing, it is passing the characters $ and @ to the shell within the argv array of strings.

[runeimp]

Ah, that's a bummer ☹️

[Cologler]

Work on PowerShell Core 7.4 with -cwa options:

set positional-arguments
set shell := ["pwsh", "-cwa"]

run *args:
    python -c "import sys; print(sys.argv)" @($args[1..($args.Count - 1)])

Execute just run 1 '2 3' print:

['-c', '1', '2 3']

[casey]

@Cologler That's super nice! This has been a longstanding limitation. Is -cwa a new option? If -cwa is widely available, we should probably update the readme to suggest using -CommandWithArgs instead of `-Command.

[Cologler]

@casey CommandWithArgs is an experimental feature added in 7.4.

Source: https://learn.microsoft.com/en-us/powershell/module/microsoft.powershell.core/about/about_pwsh?view=powershell-7.4

[casey]

Gotcha. I added a note to the readme in #2404. I think this is "fixed" and can be closed, since there's a good workaround.

[Cologler]

@casey Unlike $@ in sh, powershell must use @($args[1..($args.Count - 1)]) to skip the first argument pass from just.

[casey]

@Cologler Thanks! Updating the example in the readme to be more complete in #2405.