This adds support for (limited) mutable variables. Mutable variables are created with mut much the same way immutable variables are made with let.
Mutable variables allow mutation via the assignment operator (=).
❯ mut x = 100
❯ $x = 200
❯ print $x
200
Mutable variables are limited in that they're only tended to be used in the local code block. Trying to capture a local variable will result in an error:
❯ mut x = 123; {|| $x }
Error: nu::parser::expected_keyword (link)
× Capture of mutable variable.
The intent of this limitation is to reduce some of the issues with mutable variables in general: namely they make code that's harder to reason about. By reducing the scope that a mutable variable can be used it, we can help create local reasoning about them.
Mutation can occur with fields as well, as in this case:
❯ mut y = {abc: 123}
❯ $y.abc = 456
❯ $y
On a historical note: mutable variables are something that we resisted for quite a long time, leaning as much as we could on the functional style of pipelines and dataflow. That said, we've watched folks struggle to work with reduce as an approximation for patterns that would be trivial to express with local mutation. With that in mind, we're leaning towards the happy path.
Allows use of slightly optimized variants that check if they have to use
the heavier vte parser. Tries to avoid unnnecessary allocations. Initial
performance characteristics proven out in #4378.
Also reduces boilerplate with right-ward drift.
* Apply clippy fix to avoid extra allocation
error: `format!(..)` appended to existing `String`
--> crates/nu-engine/src/documentation.rs:82:9
|
82 | long_desc.push_str(&format!("\n{G}Subcommands{RESET}:\n"));
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
|
= note: `-D clippy::format-push-string` implied by `-D warnings`
= help: consider using `write!` to avoid the extra allocation
= help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#format_push_string
error: `format!(..)` appended to existing `String`
--> crates/nu-engine/src/documentation.rs:96:9
|
96 | long_desc.push_str(&format!("\n{G}Parameters{RESET}:\n"));
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
|
= help: consider using `write!` to avoid the extra allocation
= help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#format_push_string
error: `format!(..)` appended to existing `String`
--> crates/nu-engine/src/documentation.rs:128:9
|
128 | long_desc.push_str(&format!("\n{}Examples{}:", G, RESET));
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
|
= help: consider using `write!` to avoid the extra allocation
= help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#format_push_string
error: `format!(..)` appended to existing `String`
--> crates/nu-engine/src/documentation.rs:202:5
|
202 | long_desc.push_str(&format!("\n{}Flags{}:\n", G, RESET));
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
|
= help: consider using `write!` to avoid the extra allocation
= help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#format_push_string
error: could not compile `nu-engine` due to 4 previous errors
* Apply clippy fix to avoid deref on an immutable reference
error: deref on an immutable reference
--> crates/nu-command/src/dataframe/eager/sql_context.rs:188:77
|
188 | SetExpr::Select(select_stmt) => self.execute_select(&*select_stmt)?,
| ^^^^^^^^^^^^^
|
= note: `-D clippy::borrow-deref-ref` implied by `-D warnings`
= help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#borrow_deref_ref
help: if you would like to reborrow, try removing `&*`
|
188 | SetExpr::Select(select_stmt) => self.execute_select(select_stmt)?,
| ~~~~~~~~~~~
help: if you would like to deref, try using `&**`
|
188 | SetExpr::Select(select_stmt) => self.execute_select(&**select_stmt)?,
| ~~~~~~~~~~~~~~
error: deref on an immutable reference
--> crates/nu-command/src/database/values/dsl/expression.rs:252:15
|
252 | match &*expr {
| ^^^^^^ help: if you would like to reborrow, try removing `&*`: `expr`
|
= help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#borrow_deref_ref
error: could not compile `nu-command` due to 2 previous errors
* Add source-env test for dynamic path
* Use correct module ID for env overlay imports
* Remove parser check from "overlay list"
It would cause unnecessary errors from some inner scope if some
overlay module was also defined in some inner scope.
* Restore Cargo.lock back
* Remove comments
* start working on source-env
* WIP
* Get most tests working, still one to go
* Fix file-relative paths; Report parser error
* Fix merge conflicts; Restore source as deprecated
* Tests: Use source-env; Remove redundant tests
* Fmt
* Respect hidden env vars
* Fix file-relative eval for source-env
* Add file-relative eval to "overlay use"
* Use FILE_PWD only in source-env and "overlay use"
* Ignore new tests for now
This will be another issue
* Throw an error if setting FILE_PWD manually
* Fix source-related test failures
* Fix nu-check to respect FILE_PWD
* Fix corrupted spans in source-env shell errors
* Fix up some references to old source
* Remove deprecation message
* Re-introduce deleted tests
Co-authored-by: kubouch <kubouch@gmail.com>
