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remove let-env, focus on mutating $env (#9574)

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# 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)
This commit is contained in:
JT
2023-07-01 07:57:51 +12:00
committed by GitHub
parent 11132f7353
commit 4af24363c2
51 changed files with 371 additions and 402 deletions
Download Patch File Download Diff File Expand all files Collapse all files

86
crates/nu-engine/src/eval.rs
View File

@ -489,51 +489,63 @@ pub fn eval_expression(
Err(ShellError::AssignmentRequiresMutableVar { lhs_span: lhs.span })
}
}
Expr::FullCellPath(cell_path) => match &cell_path.head.expr {
Expr::Var(var_id) | Expr::VarDecl(var_id) => {
// The $env variable is considered "mutable" in Nushell.
// As such, give it special treatment here.
let is_env = var_id == &ENV_VARIABLE_ID;
if is_env || engine_state.get_var(*var_id).mutable {
let mut lhs =
eval_expression(engine_state, stack, &cell_path.head)?;
Expr::FullCellPath(cell_path) => {
match &cell_path.head.expr {
Expr::Var(var_id) | Expr::VarDecl(var_id) => {
// The $env variable is considered "mutable" in Nushell.
// As such, give it special treatment here.
let is_env = var_id == &ENV_VARIABLE_ID;
if is_env || engine_state.get_var(*var_id).mutable {
let mut lhs =
eval_expression(engine_state, stack, &cell_path.head)?;
lhs.upsert_data_at_cell_path(&cell_path.tail, rhs)?;
if is_env {
if cell_path.tail.is_empty() {
return Err(ShellError::CannotReplaceEnv {
span: cell_path.head.span,
});
}
lhs.upsert_data_at_cell_path(&cell_path.tail, rhs)?;
if is_env {
if cell_path.tail.is_empty() {
return Err(ShellError::CannotReplaceEnv {
span: cell_path.head.span,
});
}
// The special $env treatment: for something like $env.config.history.max_size = 2000,
// get $env.config (or whichever one it is) AFTER the above mutation, and set it
// as the "config" environment variable.
let vardata = lhs.follow_cell_path(
&[cell_path.tail[0].clone()],
false,
)?;
match &cell_path.tail[0] {
PathMember::String { val, .. } => {
stack.add_env_var(val.to_string(), vardata);
}
// In case someone really wants an integer env-var
PathMember::Int { val, .. } => {
stack.add_env_var(val.to_string(), vardata);
// The special $env treatment: for something like $env.config.history.max_size = 2000,
// get $env.config (or whichever one it is) AFTER the above mutation, and set it
// as the "config" environment variable.
let vardata = lhs.follow_cell_path(
&[cell_path.tail[0].clone()],
false,
)?;
match &cell_path.tail[0] {
PathMember::String { val, span, .. } => {
if val == "FILE_PWD"
|| val == "CURRENT_FILE"
|| val == "PWD"
{
return Err(ShellError::AutomaticEnvVarSetManually {
envvar_name: val.to_string(),
span: *span,
});
} else {
stack.add_env_var(val.to_string(), vardata);
}
}
// In case someone really wants an integer env-var
PathMember::Int { val, .. } => {
stack.add_env_var(val.to_string(), vardata);
}
}
} else {
stack.add_var(*var_id, lhs);
}
Ok(Value::nothing(cell_path.head.span))
} else {
stack.add_var(*var_id, lhs);
Err(ShellError::AssignmentRequiresMutableVar {
lhs_span: lhs.span,
})
}
Ok(Value::nothing(cell_path.head.span))
} else {
Err(ShellError::AssignmentRequiresMutableVar {
lhs_span: lhs.span,
})
}
_ => Err(ShellError::AssignmentRequiresVar { lhs_span: lhs.span }),
}
_ => Err(ShellError::AssignmentRequiresVar { lhs_span: lhs.span }),
},
}
_ => Err(ShellError::AssignmentRequiresVar { lhs_span: lhs.span }),
}
}