Comment 2 for bug 806398

Luis, do you want me to mangle this into shape, or do you want comments to finish it yourself?

Assuming the latter.

I would mildly prefer this to be implement this as

  (return-from open
    (tagbody :restart
       (let* ((pathname ...) ...)
          (flet ((open-error (...)
                     (%open-error ...additional args and defaults...
                                           (lambda (&key ...)
                                              ...set values based on keys...
                                              (go :restart)))
             ...body-of-open...))))

instead of a recursive call. Where %OPEN-ERROR would be an out of line function with a big RESTART-CASE in it, and all errors in OPEN going to it through OPEN-ERROR -- using :TEST clause in the RESTART-CASE to decide which restarts to activate.

While in the area, other useful restarts might be to switch to:

  :IF-EXISTS :APPEND
  :IF-DOES-NOT-EXIST :CREATE

and to return NIL instead of the stream, simply retry without doing anything else, USE-VALUE for a different pathname, and finally to create missing directories...

...but that might count as heroic effort. :)

However, if the error signaling and restarts are moved out of line, it would not clutter OPEN and such heroic effort can be later expanded much more easily.