Some zsh magic to detect and change the current Flutter version needed by an app in the current directory

.zshrc

# Add this to your ~/.zshrc AFTER the last export PATH="" that is currenttly defined

# Change these to reflect where do you have Flutter installed
export FLUTTER_STABLE_PATH="$HOME/dev/flutter/bin"
export FLUTTER_BETA_PATH="$HOME/dev/flutter-beta/bin"
export FLUTTER_MASTER_PATH="$HOME/dev/flutter-master/bin"

export BASE_PATH=$PATH
# Using 💙 until we can get a Flutter emoji :)
function useFlutterStable() {
    export RPROMPT=""
    export PATH="$BASE_PATH:$FLUTTER_STABLE_PATH"
}

function useFlutterBeta() {
    export RPROMPT="💙 %{$fg[yellow]%}Beta%{$reset_color%}"
    export PATH="$BASE_PATH:$FLUTTER_BETA_PATH"
}

function useFlutterMaster() {
    export RPROMPT="💙 %{$fg_bold[red]%}Master%{$reset_color%}"
    export PATH="$BASE_PATH:$FLUTTER_MASTER_PATH"
}

_check_needed_flutter_version() {
    # TODO : We need to look on the root of the flutter app, but for now this
    # will work
    VERSION=`cat $PWD/.flutter_version 2>/dev/null || echo 'stable'`

    if [ "master" = "$VERSION" ] ; then
        useFlutterMaster
    fi
    if [ "stable" = "$VERSION" ] ; then
        useFlutterStable
    fi
    if [ "beta" = "$VERSION" ] ; then
        useFlutterBeta
    fi
}

useFlutterStable
precmd_functions+=(_check_needed_flutter_version)