nushell/crates/nu-command/src
JT 4af24363c2
remove let-env, focus on mutating $env (#9574)
# Description

For years, Nushell has used `let-env` to set a single environment
variable. As our work on scoping continued, we refined what it meant for
a variable to be in scope using `let` but never updated how `let-env`
would work. Instead, `let-env` confusingly created mutations to the
command's copy of `$env`.

So, to help fix the mental model and point people to the right way of
thinking about what changing the environment means, this PR removes
`let-env` to encourage people to think of it as updating the command's
environment variable via mutation.

Before:

```
let-env FOO = "BAR"
```

Now:

```
$env.FOO = "BAR"
```

It's also a good reminder that the environment owned by the command is
in the `$env` variable rather than global like it is in other shells.

# User-Facing Changes

BREAKING CHANGE BREAKING CHANGE

This completely removes `let-env FOO = "BAR"` so that we can focus on
`$env.FOO = "BAR"`.

# Tests + Formatting
<!--
Don't forget to add tests that cover your changes.

Make sure you've run and fixed any issues with these commands:

- `cargo fmt --all -- --check` to check standard code formatting (`cargo
fmt --all` applies these changes)
- `cargo clippy --workspace -- -D warnings -D clippy::unwrap_used -A
clippy::needless_collect -A clippy::result_large_err` to check that
you're using the standard code style
- `cargo test --workspace` to check that all tests pass
- `cargo run -- crates/nu-std/tests/run.nu` to run the tests for the
standard library

> **Note**
> from `nushell` you can also use the `toolkit` as follows
> ```bash
> use toolkit.nu # or use an `env_change` hook to activate it
automatically
> toolkit check pr
> ```
-->

# After / Before Submitting
integration scripts to update:
- ✔️
[starship](https://github.com/starship/starship/blob/master/src/init/starship.nu)
- ✔️
[virtualenv](https://github.com/pypa/virtualenv/blob/main/src/virtualenv/activation/nushell/activate.nu)
- ✔️
[atuin](https://github.com/ellie/atuin/blob/main/atuin/src/shell/atuin.nu)
(PR: https://github.com/ellie/atuin/pull/1080)
- 
[zoxide](https://github.com/ajeetdsouza/zoxide/blob/main/templates/nushell.txt)
(PR: https://github.com/ajeetdsouza/zoxide/pull/587)
- ✔️
[oh-my-posh](https://github.com/JanDeDobbeleer/oh-my-posh/blob/main/src/shell/scripts/omp.nu)
(pr: https://github.com/JanDeDobbeleer/oh-my-posh/pull/4011)
2023-07-01 07:57:51 +12:00
..
charting revert: move to ahash (#9464) 2023-06-18 15:27:57 +12:00
conversions convert a string to a raw binary string of 0s and 1s (#9534) 2023-06-28 13:04:07 -05:00
database Improve type hovers (#9515) 2023-06-29 05:19:48 +12:00
date Update some help examples (#8759) 2023-04-05 18:36:00 -05:00
debug remove let-env, focus on mutating $env (#9574) 2023-07-01 07:57:51 +12:00
deprecated remove let-env, focus on mutating $env (#9574) 2023-07-01 07:57:51 +12:00
env remove let-env, focus on mutating $env (#9574) 2023-07-01 07:57:51 +12:00
experimental fix is-admin example (#9350) 2023-06-03 15:11:14 -05:00
filesystem fix cd permissions when user belongs to folder group (#9531) 2023-06-30 11:03:26 +02:00
filters rename: add -b flag to support closure input (#8948) 2023-06-29 10:24:34 -05:00
formats Apply nightly clippy fixes (#9482) 2023-06-20 10:17:33 +02:00
generators Document and critically review ShellError variants - Ep. 2 (#8326) 2023-03-06 11:31:07 +01:00
hash move common tools from nu-command to nu-cmd-base (#9455) 2023-06-22 14:45:54 -07:00
help Break up interdependencies of command crates (#9429) 2023-06-14 23:12:55 +02:00
math revert: move to ahash (#9464) 2023-06-18 15:27:57 +12:00
misc REFACTOR: move source out of deprecated commands (#9060) 2023-05-04 00:02:03 +02:00
network move common tools from nu-command to nu-cmd-base (#9455) 2023-06-22 14:45:54 -07:00
path revert: move to ahash (#9464) 2023-06-18 15:27:57 +12:00
platform add input_output type to input list to return string (#9557) 2023-06-29 08:27:25 -05:00
random Document and critically review ShellError variants - Ep. 3 (#8340) 2023-03-06 18:33:09 +01:00
shells Fix usage for the exit command. (#9450) 2023-06-16 10:09:02 +02:00
strings A new subcommand to str, str-expand. (#9290) 2023-06-28 12:57:44 -05:00
system revert: move to ahash (#9464) 2023-06-18 15:27:57 +12:00
viewers nu-table/ Fix indexing issue for table --expand (#9484) 2023-06-20 20:27:00 +12:00
default_context.rs remove let-env, focus on mutating $env (#9574) 2023-07-01 07:57:51 +12:00
example_test.rs remove let-env, focus on mutating $env (#9574) 2023-07-01 07:57:51 +12:00
hook.rs cratification: move the bytes command to nu-cmd-extra (#9509) 2023-06-23 12:23:08 -07:00
lib.rs cratification: move the bytes command to nu-cmd-extra (#9509) 2023-06-23 12:23:08 -07:00
progress_bar.rs cp progress bar implementation (#8012) 2023-02-22 11:57:38 -08:00
sort_utils.rs Support passing an empty list to sort, uniq, sort-by, and uniq-by (issue #5957) (#8669) 2023-03-29 19:55:38 -07:00