pyenv-tmp

#!/usr/bin/env bash
#
# Summary: Creates a temporary virtualenv based on a version
#
# Usage: pyenv COMMAND [version] [tmp-name]
#
# When no version is provided it'll use the currently configured
# one.
#

set -e
[ -n "$PYENV_DEBUG" ] && set -x

VERSION="$1"
NAME="$2"
[ -z "$VERSION" ] && VERSION=$( pyenv version-name )
[ -z "$NAME" ] && NAME=$(mktemp -u "tmp-$VERSION-XXXX")

pyenv versions --bare | grep -qx "$VERSION" || {
  >&2 echo "WARNING: triggering $VERSION install"
  pyenv install "$VERSION"
}

>&2 echo "Creating temporary virtualenv '$NAME' (from $VERSION)..."
pyenv virtualenv "$VERSION" "$NAME" &> /dev/null || {
  >&2 echo 'ERROR: Unable to create temporary virtualenv'
  exit 1
}

trap 'pyenv uninstall -f "$NAME"' EXIT

>&2 echo "Entering shell with virtualenv '$NAME' (removed on exit)"
PYENV_VERSION="$NAME" "$SHELL"

>&2 echo "Destroying temporary virtualenv '$NAME'..."
# the EXIT trap will uninstall it