brew_python.zsh

#!/usr/bin/env zsh
# Add or subtract python@
zmodload zsh/pcre

brew_python function() {
    __add_version () {
        version="$1"
        if [[ ! "$version" =~ "^[2-3]\.[0-9]+$" ]]; then
            echo "Not a valid python version" 1>&2
            return 1
        fi

        if ! brew list "python@$version" &>/dev/null; then
            echo "Error: python@$version not installed" 1>&2
            return 1
        fi
        local bin_path="$(brew --prefix python@$version)/bin"
        local libexec_bin_path="$(brew --prefix python@$version)/libexec/bin"
        path=($bin_path $libexec_bin_path $path)
        export PATH
    }

    __remove_version () {
        version="$1"
        if [[ ! "$version" =~ "^[2-3]\.[0-9]+$" ]]; then
            echo "Not a valid python version" 1>&2
            return 1
        fi
        prefix="$(brew --prefix python@$version 2>/dev/null)" || echo "python@$version not installed" >&2 && return 1
        echo "Removing ${path:#$prefix/bin}:${path:#$prefix/libexec/bin} from PATH"
        path=(${path:#$prefix/bin})
        path=(${path:#$prefix/libexec/bin})
    }

    if [[ -z "$@" ]]; then
        echo "Usage: version" 1>&2
        return 1
    fi
    typeset subcmd="$1"
    case $subcmd in
        remove)
            __remove_version $2
            ;;
        add)
            __add_version $2
            ;;
        *)
            echo "Usage: version [remove|add] python-version" 1>&2
            return 1
    esac
}