zsh_async.zsh

# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.

# This snippet of code is released into the public domain.
# However, an attribution link is welcome.

# Run a job in the foreground after TIMEOUT seconds
# to make prompt rendering in a new session faster and more responsive.
# for example: 
# pyenv_loader() {
#       unset -f pyenv_load
#       [[ -z "$PYENV_HOME" ]] && export PYENV_HOME="$HOME/.pyenv"
#       export PATH="$PYENV_HOME/bin:$PATH"
#       eval "$(pyenv init -)" 
# }
# run_after_seconds pyenv_loader 0.5
run_after_seconds() {
  if [[ $# != 2 ]]; then
    echo run_after_seconds FUNC TIMEOUT
    return
  fi
  local func=$1
  local timeout=$2
  local int FD
  wrapper() {
    local fd=$1
    local func
    # read -r -u $fd func
    # or
    func="$(<&$fd)"
    $func
    zle -F $fd
    exec {fd}<&-
  }
  exec {FD}< <(sleep $timeout; printf "%s" "$func";)
  zle -F $FD wrapper
}