Consider implementing `rustup shell`

[brson]

Like rbenv shell. This allows you to configure the running shell to use a particular toolchain. It's super convenient but the way it does it is pretty nasty: .bashrc runs eval $(rbenv init), which creates an rbenv shell function that intercepts rbenv shell in order to inject environment variables into the running shell.

[whitequark]

Consider going the opam route: they explicitly instruct to use eval $(opam config env), which is quite clean. And whoever desires it can always add something like...

opam() { 
  command opam $* && 
    if [ "$1" = "switch" ]; then 
      eval $(command opam config env);
    fi
}

to their bashrc.

[chriskrycho]

@brson, I'm with you on it being a nasty way to do that. It may well not be worth the tradeoff for the convenience—not least because while there are times it's handy with Ruby and Python, those mostly have to do with the way they are used as scripting glue, rather than for normal full-on development. I suspect that the ability to do something like rustup run nightly <command> would be sufficient for those cases where anyone's needing it presently.

[SimonSapin]

Rather than messing with the running shell, isn’t it better to start a new shell? Like rustup run nightly bash (or whatever your shell is instead of bash). That way, "deactivate" is simply exit, returning to the outer shell.

[whitequark]

This messes up history on default configuration of bash (for example).

[marmistrz]

I added the following to my ~/.zshrc

if (( ${+RUSTUP_HOME} )); then
    PROMPT="(rustup) $PROMPT"
fi

and just use rustup run nightly $SHELL

Anyway, rustup shell nightly would be handy.