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

71 lines
2.2 KiB
Rust

use nu_protocol::ast::Call;
use nu_protocol::engine::{Command, EngineState, Stack};
use nu_protocol::{
Category, Example, PipelineData, ShellError, Signature, SyntaxShape, Type, Value,
};
#[derive(Clone)]
pub struct Module;
impl Command for Module {
fn name(&self) -> &str {
"module"
}
fn usage(&self) -> &str {
"Define a custom module."
}
fn signature(&self) -> nu_protocol::Signature {
Signature::build("module")
.input_output_types(vec![(Type::Nothing, Type::Nothing)])
.allow_variants_without_examples(true)
.required("module", SyntaxShape::String, "module name or module path")
.optional(
"block",
SyntaxShape::Block,
"body of the module if 'module' parameter is not a module path",
)
.category(Category::Core)
}
fn extra_usage(&self) -> &str {
r#"This command is a parser keyword. For details, check:
https://www.nushell.sh/book/thinking_in_nu.html"#
}
fn is_parser_keyword(&self) -> bool {
true
}
fn run(
&self,
_engine_state: &EngineState,
_stack: &mut Stack,
_call: &Call,
_input: PipelineData,
) -> Result<PipelineData, ShellError> {
Ok(PipelineData::empty())
}
fn examples(&self) -> Vec<Example> {
vec![
Example {
description: "Define a custom command in a module and call it",
example: r#"module spam { export def foo [] { "foo" } }; use spam foo; foo"#,
result: Some(Value::test_string("foo")),
},
Example {
description: "Define an environment variable in a module",
example: r#"module foo { export-env { $env.FOO = "BAZ" } }; use foo; $env.FOO"#,
result: Some(Value::test_string("BAZ")),
},
Example {
description: "Define a custom command that participates in the environment in a module and call it",
example: r#"module foo { export def-env bar [] { $env.FOO_BAR = "BAZ" } }; use foo bar; bar; $env.FOO_BAR"#,
result: Some(Value::test_string("BAZ")),
},
]
}
}