Add `path self` command for getting absolute paths to files at parse time by Bahex · Pull Request #14303 · nushell/nushell

Bahex · 2024-11-11T09:05:40Z

Alternative solution to:

Making $env.FILE_PWD and $env.CURRENT_FILE constants, renaming them to be more descriptive, and adding similar constants for any source file #12195

The other approach:

Add parse-time constant $NU_CURRENT_FILE #14305

Description

Adds ~~path const~~ path self, a parse-time only command for getting the absolute path of the source file containing it, or any file relative to the source file.

Useful for any script or module that makes use of non nuscript files.
Removes the need for $env.CURRENT_FILE and $env.FILE_PWD.
Can be used in modules, sourced files or scripts.

Examples

# ~/.config/nushell/scripts/foo.nu
const paths = {
    self: (path self),
    dir: (path self .),
    sibling: (path self sibling),
    parent_dir: (path self ..),
    cousin: (path self ../cousin),
}

export def main [] {
    $paths
}

> use foo.nu
> foo
╭────────────┬────────────────────────────────────────────╮
│ self       │ /home/user/.config/nushell/scripts/foo.nu  │
│ dir        │ /home/user/.config/nushell/scripts         │
│ sibling    │ /home/user/.config/nushell/scripts/sibling │
│ parent_dir │ /home/user/.config/nushell                 │
│ cousin     │ /home/user/.config/nushell/cousin          │
╰────────────┴────────────────────────────────────────────╯

Trying to run in a non-const context

> path self
Error:   × this command can only run during parse-time
   ╭─[entry #1:1:1]
 1 │ path self 
   · ─────┬────
   ·      ╰── can't run after parse-time
   ╰────
  help: try assigning this command's output to a const variable

Trying to run in the REPL i.e. not in a file

> const foo = path self
Error:   × Error: nu::shell::file_not_found
  │ 
  │   × File not found
  │    ╭─[entry #3:1:13]
  │  1 │ const foo = path self
  │    ·             ─────┬────
  │    ·                  ╰── Couldn't find current file
  │    ╰────
  │ 
   ╭─[entry #3:1:13]
 1 │ const foo = path self
   ·             ─────┬────
   ·                  ╰── Encountered error during parse-time evaluation
   ╰────

Comparison with #14305

Pros

Self contained implementation, does not require changes in the parser.
More concise usage, especially with parent directories.

amtoine · 2024-11-20T17:29:38Z

an early review: following what's in #12195 sounds better and simpler to me than having a new command 😋

devyn · 2024-11-23T22:08:00Z

Yeah, I'm also not sure I like this just because the name is not very self-explanatory. If you're reading this and you don't know about it already you're probably not going to know what it does. Whereas $FILE_PWD | path join "foo.nu" seems very straightforward

QORTEC · 2024-11-24T21:15:09Z

I would suggest renaming path const to path self, this makes purpose of the command more straightforward at a glance.

If we reuse the syntax of path join we get the following:

~> path self --help
Get a const of the current files path.

Optionally, append an additional path to the current files directory.

Usage:
  > path self ...(append) 

Flags:
  -h, --help: Display the help message for this command

Parameters:
  ...append <string>: Path to append to the current files directory.

Input/output types:
  ╭───┬──────────────┬──────────────╮
  │ # │    input     │    output    │
  ├───┼──────────────┼──────────────┤
  │ 0 │ nothing      │ string       │
  ╰───┴──────────────┴──────────────╯

Examples:
  Get the path of the current file
  > path self
  /home/scripts/foo.nu

  Get the directory of the current file
  > path self .
  /home/scripts

  Get the parent directory of the current file
  > path self ..
  /home

  Append a path to the current files directory
  > path self sibling
  /home/scripts/sibling

  From the current file go up one directory and append a path
  > path self .. cousin
  /home/../cousin

Bahex · 2024-11-25T08:47:37Z

path self is a good suggestion, thanks!

QORTEC · 2024-11-27T23:11:32Z

Trying to run in a non-const context

path const
Error:   × this command can only run during parse-time
   ╭─[entry #1:1:1]
 1 │ path const 
   · ─────┬────
   ·      ╰── can't run after parse-time
   ╰────
  help: try assigning this command's output to a const variable

I don't remember there being any nushell commands that are limited to a const context.
Does this limitation simplify the code?

Bahex · 2024-11-28T06:40:11Z

Does this limitation simplify the code?

It simplifies things immensely, and let's path const to be implemented like any other command, without requiring any modifications to the parser or IR.

It can't run after parse-time, because it wouldn't be running within the context of the file.

Not sure how to have examples run in parse-time.

Bahex · 2024-12-06T07:11:10Z

Renamed as suggested.

fdncred · 2024-12-06T14:04:13Z

@Bahex I hope you don't mind. I added a couple tweaks. The TODO wasn't needed because that's checked with the input_output_types and just tweaks your examples and help.

fdncred · 2024-12-06T14:19:30Z

Thanks for working on this!

fdncred · 2024-12-07T12:38:57Z

@Bahex I'm getting the error below when running nu --ide-check 100 /path/to/env.nu. This --ide-check parameter is used in the vscode extension to find errors.

When I put this in my env.nu or config.nu

const const_env = path self
print $"Hello, from ($const_env)!"

Am I just using it wrong or is this an edge case that is a new bug? Or maybe something needs to change in

nushell/src/ide.rs

Lines 75 to 138 in 9411458

    
           pub fn check(engine_state: &mut EngineState, file_path: &str, max_errors: &Value) { 
        
               let cwd = std::env::current_dir().expect("Could not get current working directory."); 
        
               engine_state.add_env_var("PWD".into(), Value::test_string(cwd.to_string_lossy())); 
        
               engine_state.generate_nu_constant(); 
        
               let mut working_set = StateWorkingSet::new(engine_state); 
        
               let file = std::fs::read(file_path); 
        
               let max_errors = if let Ok(max_errors) = max_errors.as_int() { 
        
                   max_errors as usize 
        
               } else { 
        
                   100 
        
               }; 
        
               if let Ok(contents) = file { 
        
                   let offset = working_set.next_span_start(); 
        
                   let block = parse(&mut working_set, Some(file_path), &contents, false); 
        
                   for (idx, err) in working_set.parse_errors.iter().enumerate() { 
        
                       if idx >= max_errors { 
        
                           // eprintln!("Too many errors, stopping here. idx: {idx} max_errors: {max_errors}"); 
        
                           break; 
        
                       } 
        
                       let mut span = err.span(); 
        
                       span.start -= offset; 
        
                       span.end -= offset; 
        
                       let msg = err.to_string(); 
        
                       println!( 
        
                           "{}", 
        
                           json!({ 
        
                               "type": "diagnostic", 
        
                               "severity": "Error", 
        
                               "message": msg, 
        
                               "span": { 
        
                                   "start": span.start, 
        
                                   "end": span.end 
        
                               } 
        
                           }) 
        
                       ); 
        
                   } 
        
                   let flattened = flatten_block(&working_set, &block); 
        
                   for flat in flattened { 
        
                       if let FlatShape::VarDecl(var_id) = flat.1 { 
        
                           let var = working_set.get_variable(var_id); 
        
                           println!( 
        
                               "{}", 
        
                               json!({ 
        
                                   "type": "hint", 
        
                                   "typename": var.ty.to_string(), 
        
                                   "position": { 
        
                                       "start": flat.0.start - offset, 
        
                                       "end": flat.0.end - offset 
        
                                   } 
        
                               }) 
        
                           ); 
        
                       } 
        
                   } 
        
               } 
        
           }

# Description fixes [this](#14303 (comment)) where lsp and ide integration would produce the following error --- ```sh nu --ide-check 100 "/path/to/env.nu" ``` with ```nu const const_env = path self ``` would lead to ``` Error: nu::shell::file_not_found × File not found ╭─[/path/to/env.nu:1:19] 1 │ const const_env = path self · ────┬──── · ╰── Couldn't find current file ╰──── ``` # Tests + Formatting - :green_circle: `cargo fmt --all` - :green_circle: `cargo clippy --workspace`

suimong · 2024-12-07T16:35:04Z

Hey guys, really love this command, but just have a quick question about the semantics: I see that the returned path is expanded, ie if a nushell file is a symlink, path self will return the path to the source file rather than the symlink. While it is in line with $env.CURRENT_FILE, I'm just wondering what is the rationale that favors returning path expanded over as-is. To me there are use cases where getting the as-is path is desired (eg if the nushell script or module is installed by GNU stow), and I couldn't find an argument/use case against it. This is a genuine question and I'd really appreciate some clarification. Thanks in advance!

…self` Nushell 0.101+) See: nushell/nushell#14303

vyadh · 2024-12-07T16:55:56Z

This is super useful for nu-test as I needed it where $env.CURRENT_FILE wasn't defined (in a nu -c context). Thanks @Bahex

Bahex · 2024-12-08T08:23:51Z

@suimong It's mostly because of how nushell resolves the paths to modules/files. For example

❯ ls -l | select name type target
╭─#─┬──name──┬──type───┬─target─╮
│ 0 │ bar.nu │ symlink │ foo.nu │
│ 1 │ foo.nu │ file    │        │
╰─#─┴──name──┴──type───┴─target─╯
❯ use bar.nu
❯ scope modules | select name file | where name in [foo bar]
╭─#─┬─name─┬────────────file────────────╮
│ 0 │ foo  │ /tmp/tmp.7r6aCwuV4y/foo.nu │
╰─#─┴─name─┴────────────file────────────╯

A possible workaround for your use case would be to have short files that set some constants and then source the file that contains the actual logic.

const ENTRY_POINT = (path self .)
source logic.nu

# logic.nu
# rather than using `path self` directly, use the pre-set constant variable
do-something $ENTRY_POINT

suimong · 2024-12-08T16:14:53Z

I see. @Bahex thanks for the explanation and the workaround. Still, having path find is a huge, huge empowerment for Nushell as a scripting language. Thanks again for making it happen!

fdncred · 2024-12-09T00:33:48Z

path find?

suimong · 2024-12-09T10:59:45Z

path find?

Sorry I don't follow. We don't seem to have this command? Or is it a new command proposed in the spirit of path self?

fdncred · 2024-12-09T12:33:00Z

You mention it above and I'm wondering the same thing, what is path find?

suimong · 2024-12-09T15:18:02Z

Ah, stupid me. I mean path self of course...

sholderbach added the A:const-eval Evaluation of const expressions at parse time if possible label Nov 11, 2024

Bahex force-pushed the const-path branch from e3bc7f2 to 7acdb26 Compare November 17, 2024 10:10

Bahex mentioned this pull request Nov 24, 2024

Add parse-time constant $NU_CURRENT_FILE #14305

Closed

Bahex added 4 commits December 6, 2024 09:07

add path const for getting absolute paths to files at parse time

223a219

Fix typo

aec36d5

Allow passing test witout examples.

213e6c9

Not sure how to have examples run in parse-time.

Rename path const to path self

a8794fc

Bahex force-pushed the const-path branch from 7acdb26 to a8794fc Compare December 6, 2024 06:52

cargo fmt

18dd1f8

Bahex changed the title ~~Add path const command for getting absolute paths to files at parse time~~ Add path self command for getting absolute paths to files at parse time Dec 6, 2024

Add examples

86f7f2d

Bahex marked this pull request as ready for review December 6, 2024 11:55

a few minor tweaks

26c51de

fdncred merged commit 8771872 into nushell:main Dec 6, 2024

github-actions bot added this to the v0.101.0 milestone Dec 6, 2024

Bahex mentioned this pull request Dec 7, 2024

lsp and --ide-check fix for path self related diagnostics #14538

Merged

vyadh added a commit to vyadh/nutest that referenced this pull request Dec 7, 2024

Fixed a problem running tests from another directory (requires `path …

15d9070

…self` Nushell 0.101+) See: nushell/nushell#14303

Bahex deleted the const-path branch March 22, 2026 12:35

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Description

Examples

Comparison with #14305

Pros

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