nushell/src
Bob Hyman 9e9fe83bfd
Parameter defaults to $nu.scope.commands (#9152)
(*third* try at posting this PR, #9104, like #9084, got polluted with
unrelated commits. I'm never going to pull from the github feature
branch again!)

# Description
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Show parameter defaults in scope command signature, where they're
available for display by help.
per https://github.com/nushell/nushell/issues/8928.

I found unexpected ramifications in one completer (NuHelpCompleter) and
plugins, which both use the flag-formatting routine from builtin help.
For the moment I made the minimum necessary changes to get the mainline
scenario to pass tests and run. But we should circle back on what to do
with plugins and help completer..

# User-Facing Changes
<!-- List of all changes that impact the user experience here. This
helps us keep track of breaking changes. -->
1. New `parameter_default` column to `signatures` table in
`$nu.scope.commands`
It is populated with whatever parameters can be defaulted: currently
positional args and named flags.
2. Built in help (both `help <command>` and `<command> --help` will
display the defaults
3. Help completer will display defaults for flags, but not for
positionals.

Example:
A custom command with some default parameters:
```
〉cat ~/work/dflts.nu 
# sample function to show defaults in help
export def main [
    arg1: string        # mandatory positional
    arg2:string=abc     # optional positional
    --switch            # no default here
    --named:int         # named flag, no default
    --other:string=def  # flag 
    --hard:record<foo:int bar:string, bas:bool> # default can be compound type
            = {foo:22, bar:"other worlds", bas:false}
] { {arg1: $arg1,
    arg2: $arg2,
    switch: $switch,
    named: $named,
    other: $other,
    hard: $hard, }
}

〉use ~/work/dflts.nu

〉$nu.scope.commands | where name == 'dflts' | get signatures.0.any | reject short_flag description custom_completion
╭───┬────────────────┬────────────────┬──────────────────────────────────────────┬─────────────┬───────────────────────────╮
│ # │ parameter_name │ parameter_type │               syntax_shape               │ is_optional │     parameter_default     │
├───┼────────────────┼────────────────┼──────────────────────────────────────────┼─────────────┼───────────────────────────┤
│ 0 │                │ input          │ any                                      │ false       │                           │
│ 1 │ arg1           │ positional     │ string                                   │ false       │                           │
│ 2 │ arg2           │ positional     │ string                                   │ true        │ abc                       │
│ 3 │ switch         │ switch         │                                          │ true        │                           │
│ 4 │ named          │ named          │ int                                      │ true        │                           │
│ 5 │ other          │ named          │ string                                   │ true        │ def                       │
│ 6 │ hard           │ named          │ record<foo: int, bar: string, bas: bool> │ true        │ ╭───────┬───────────────╮ │
│   │                │                │                                          │             │ │ foo   │ 22            │ │
│   │                │                │                                          │             │ │ bar   │ other worlds  │ │
│   │                │                │                                          │             │ │ bas   │ false         │ │
│   │                │                │                                          │             │ ╰───────┴───────────────╯ │
│ 7 │                │ output         │ any                                      │ false       │                           │
╰───┴────────────────┴────────────────┴──────────────────────────────────────────┴─────────────┴───────────────────────────╯

〉help dflts
sample function to show defaults in help

Usage:
  > dflts {flags} <arg1> (arg2) 

Flags:
  --switch - switch -- no default here
  --named <Int> - named flag, typed, but no default
  --other <String> - flag with default (default: 'def')
  --hard <Record([("foo", Int), ("bar", String), ("bas", Boolean)])> - default can be compound type (default: {foo: 22, bar: 'other worlds', bas: false})
  -h, --help - Display the help message for this command

Parameters:
  arg1 <string>: mandatory positional
  arg2 <string>: optional positional (optional, default: 'abc')
```

Compared to (relevant bits of) help output previously:
```
Flags:
  -h, --help - Display the help message for this command
  -, --switch - no default here
  -, --named <int> - named flag, no default
  -, --other <string> - flag
  -, --hard <record<foo: int, bar: string, bas: bool>> - default can be compound type

Signatures:
  <any> | dflts <string> <string> -> <any>

Parameters:
  arg1 <string>: mandatory positional
  (optional) arg2 <string>: optional positional
```

# Tests + Formatting
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# After Submitting
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2023-05-11 13:59:56 -05:00
..
tests Parameter defaults to $nu.scope.commands (#9152) 2023-05-11 13:59:56 -05:00
command.rs add --ide-ast for a simplistic ast for editors (#8995) 2023-04-28 08:51:51 -05:00
config_files.rs Fix warning on declared config variable that originates from commands (#8891) 2023-04-26 09:21:51 -05:00
ide.rs add --ide-ast for a simplistic ast for editors (#8995) 2023-04-28 08:51:51 -05:00
logger.rs Use variable names directly in the format strings (#7906) 2023-01-29 19:37:54 -06:00
main.rs resolve standard library before ide commands (#9126) 2023-05-07 07:29:15 -05:00
README.md Remove old nushell/merge engine-q 2022-02-07 14:54:06 -05:00
run.rs REFACTOR: move the banner from the rust source to the standard library (#8406) 2023-05-10 07:05:01 -05:00
signals.rs Cleanup of src/main.rs (#7801) 2023-01-20 10:44:49 -08:00
terminal.rs Move all functions of main.rs into modules (#7803) 2023-01-20 13:20:38 -08:00
test_bins.rs REFACTOR: move the banner from the rust source to the standard library (#8406) 2023-05-10 07:05:01 -05:00
tests.rs Parameter defaults to $nu.scope.commands (#9152) 2023-05-11 13:59:56 -05:00

Nushell REPL

This directory contains the main Nushell REPL (read eval print loop) as part of the CLI portion of Nushell, which creates the nu binary itself.

Current versions of the nu binary will use the Nu argument parsing logic to parse the commandline arguments passed to nu, leaving the logic here to be a thin layer around what the core libraries.