Determining the current path of a sourced script

[Tony]

I have a bash script that will be sourced rather than run. Is there
anyway for the script to determine its location (pathname)?

Specifically, in my .bashrc I have:

  if [ -f /devel/bashrc ]; then
    . /devel/bashrc
  fi

Is there any way for /devel/bashrc to determine what directory it is
in? The reason is that /devel/bashrc is a delivered file and it might
wind up in any directory (and probably not /devel) and it needs to
know where itself is so it can set environment variables correctly.

Obviously $0 doesn't help, because that contains "bash".