nushell/crates/nu-std
Bahex 442df9e39c
Custom command attributes (#14906)
# Description
Add custom command attributes.

- Attributes are placed before a command definition and start with a `@`
character.
- Attribute invocations consist of const command call. The command's
name must start with "attr ", but this prefix is not used in the
invocation.
- A command named `attr example` is invoked as an attribute as
`@example`
-   Several built-in attribute commands are provided as part of this PR
    -   `attr example`: Attaches an example to the commands help text
        ```nushell
        # Double numbers
        @example "double an int"  { 5 | double }   --result 10
        @example "double a float" { 0.5 | double } --result 1.0
        def double []: [number -> number] {
            $in * 2
        }
        ```
    -   `attr search-terms`: Adds search terms to a command
    -   ~`attr env`: Equivalent to using `def --env`~
- ~`attr wrapped`: Equivalent to using `def --wrapped`~ shelved for
later discussion
    -   several testing related attributes in `std/testing`
- If an attribute has no internal/special purpose, it's stored as
command metadata that can be obtained with `scope commands`.
- This allows having attributes like `@test` which can be used by test
runners.
-   Used the `@example` attribute for `std` examples.
-   Updated the std tests and test runner to use `@test` attributes
-   Added completions for attributes

# User-Facing Changes
Users can add examples to their own command definitions, and add other
arbitrary attributes.

# Tests + Formatting

- 🟢 toolkit fmt
- 🟢 toolkit clippy
- 🟢 toolkit test
- 🟢 toolkit test stdlib

# After Submitting
- Add documentation about the attribute syntax and built-in attributes
- `help attributes`

---------

Co-authored-by: 132ikl <132@ikl.sh>
2025-02-11 06:34:51 -06:00
..
src Custom command attributes (#14906) 2025-02-11 06:34:51 -06:00
std Custom command attributes (#14906) 2025-02-11 06:34:51 -06:00
std-rfc Fix match blocks in std-rfc/kv implementation (#15089) 2025-02-11 11:16:57 +01:00
tests Custom command attributes (#14906) 2025-02-11 06:34:51 -06:00
Cargo.toml Move std-rfc into Nushell (#15042) 2025-02-09 09:03:37 -05:00
CONTRIBUTING.md Surprising symlink resolution for std path add (#13258) 2024-06-28 18:11:48 -05:00
LICENSE add LICENSE to nu-std (#8803) 2023-04-07 13:39:21 -07:00
README.md Change the usage misnomer to "description" (#13598) 2024-08-22 12:02:08 +02:00
testing.nu Custom command attributes (#14906) 2025-02-11 06:34:51 -06:00

Welcome to the standard library of `nushell`!

The standard library is a pure-nushell collection of custom commands which provide interactive utilities and building blocks for users writing casual scripts or complex applications.

To see what's here:

> use std
> scope commands | select name description | where name =~ "std "
#┬───────────name────────────┬───────────────────description───────────────────
0│std assert                 │Universal assert command
1│std assert equal           │Assert $left == $right
2│std assert error           │Assert that executing the code generates an error
3│std assert greater         │Assert $left > $right
4│std assert greater or equal│Assert $left >= $right
             ...                                     ...
─┴───────────────────────────┴─────────────────────────────────────────────────

🧰 Using the standard library in the REPL or in scripts

All commands in the standard library must be "imported" into the running environment (the interactive read-execute-print-loop (REPL) or a .nu script) using the use command.

You can choose to import the whole module, but then must refer to individual commands with a std prefix, e.g:

use std

std log debug "Running now"
std assert (1 == 2)

Or you can enumerate the specific commands you want to import and invoke them without the std prefix.

use std ["log debug" assert]

log debug "Running again"
assert (2 == 1)

This is probably the form of import you'll want to add to your env.nu for interactive use.

✏️ contribute to the standard library

You're invited to contribute to the standard library! See CONTRIBUTING.md for details