I keep running into to this rather trivial but annoying problem while working in slime. Emacs is running (of course), and god only knows what directory I was in when I started it up days ago. I am often working on more than one project, or I will be looking for some piece of data in a folder other than what Slime considers the "current directory" (which I usually determine by M-x d and looking to see where it's at). Whatever the case, if I want to run a few lines of code that access a different directory than the "current" one, I end up doing various ad hoc things, like figuring out the relative path between where it is and where I want it to be, or just typing out a fully-qualified pathname.

Is there a way to do this more easily? 

I know that if I put something like

(defparameter *i-am-here*
  (make-pathname :name nil :type nil :version nil :defaults (parse-namestring *load-truename*)))

in a file located in the directory I'm looking at, that the parameter will be set correctly when the file is loaded. But that begs the question, since I have to know where that file is to load it. 

What I'd like to be able to do would be something like this:

(with-open-file (fs (merge-pathnames "data.file" (directory-of-file-buffer)) :direction :input)

  ;; do stuff

)

How do other people handle this situation?

--Jeff