export def-env for core

Define a custom command that participates in the environment and export it from a module.

Signature

> export def-env (name) (params) (block)

Parameters

• name: definition name
• params: parameters
• block: body of the definition

Input/output types:

input	output
nothing	nothing

Examples

Define a custom command that participates in the environment in a module and call it

> module foo { export def-env bar [] { $env.FOO_BAR = "BAZ" } }; use foo bar; bar; $env.FOO_BAR
BAZ

Notes

This command is a parser keyword. For details, check:
  https://www.nushell.sh/book/thinking_in_nu.html

=== EXTRA NOTE ===
All blocks are scoped, including variable definition and environment variable changes.

Because of this, the following doesn't work:

export def-env cd_with_fallback [arg = ""] {
    let fall_back_path = "/tmp"
    if $arg != "" {
        cd $arg
    } else {
        cd $fall_back_path
    }
}

Instead, you have to use cd in the top level scope:

export def-env cd_with_fallback [arg = ""] {
    let fall_back_path = "/tmp"
    let path = if $arg != "" {
        $arg
    } else {
        $fall_back_path
    }
    cd $path
}