* Allow environment variables to be hidden
This change allows environment variables in Nushell to have a value of
`Nothing`, which can be set by the user by passing `$nothing` to
`let-env` and friends.
Environment variables with a value of Nothing behave as if they are not
set at all. This allows a user to shadow the value of an environment
variable in a parent scope, effectively removing it from their current
scope. This was not possible before, because a scope can not affect its
parent scopes.
This is a workaround for issues like #3920.
Additionally, this allows a user to simultaneously set, change and
remove multiple environment variables via `load-env`. Any environment
variables set to $nothing will be hidden and thus act as if they are
removed. This simplifies working with virtual environments, which rely
on setting multiple environment variables, including PATH, to specific
values, and remove/change them on deactivation.
One surprising behavior is that an environment variable set to $nothing
will act as if it is not set when querying it (via $nu.env.X), but it is
still possible to remove it entirely via `unlet-env`. If the same
environment variable is present in the parent scope, the value in the
parent scope will be visible to the user. This might be surprising
behavior to users who are not familiar with the implementation details.
An additional corner case is the the shorthand form of `with-env` does
not work with this feature. Using `X=$nothing` will set $nu.env.X to the
string "$nothing". The long-form works as expected: `with-env [X
$nothing] {...}`.
* Remove unused import
* Allow all primitives to be convert to strings
* Add the load-env command
load-env can be used to add environment variables dynamically via an
InputStream. This allows developers to create tools that output environment
variables as key-value pairs, then have the user load those variables in using
load-env. This supplants most of the need for an `eval` command, which is
mostly used in POSIX envs for setting env vars.
Fixes#3481
* fixup! Add the load-env command
The autoenv logic mutates environment variables in the running session as
it operates and decides what to do for trusted directories containing `.nu-env`
files. Few of the ways to interact with it were all in a single test function.
We separate out all the ways that were done in the single test function to document
it better. This will greatly help once we start refactoring our way out from setting
environment variables this way to just setting them to `Scope`.
This is part of an on-going effort to keep variables (`PATH` and `ENV`)
in our `Scope` and rely on it for everything related to variables.
We expect to move away from setting (`std::*`) envrironment variables in the current
running process. This is non-trivial since we need to handle cases from vars
coming in from the outside world, prioritize, and also compare to the ones
we have both stored in memory and in configuration files.
Also to send out our in-memory (in `Scope`) variables properly to external
programs once we no longer rely on `std::env` vars from the running process.
* Begin allowing comments and multiline scripts.
* clippy
* Finish moving to groups. Test pass
* Keep going
* WIP
* WIP
* BROKEN WIP
* WIP
* WIP
* Fix more tests
* WIP: alias starts working
* Broken WIP
* Broken WIP
* Variables begin to work
* captures start working
* A little better but needs fixed scope
* Shorthand env setting
* Update main merge
* Broken WIP
* WIP
* custom command parsing
* Custom commands start working
* Fix coloring and parsing of block
* Almost there
* Add some tests
* Add more param types
* Bump version
* Fix benchmark
* Fix stuff
