using (in-readtable) to select a readtable

[73budden .]

Hi!

It is SLIME-specific problem. I hope I have already described the
problem in previous posts. E.g. you type in SLIME:

>(in-package :p1)
>(in-readtable :rt1)
;  rt1 is now associated to p1
>(in-package :cl-user)
; switched to standard readtable
>(in-package :p1)
; switched to rt1
>(in-package :cl-user)
; switched to standard readtable

>(compile-file "foo")
where foo.lisp is:
(in-package :p1)
(in-readtable :rt2)
EOF
compilation failed...
>(in-package :p1)
; switched to rt2

Of course, we can not say it is completely unpredictible, but is
rather hard to predict sometimes.

When we type the same code in bare common lisp prompt, no readtable
switching occurs. This is another misleading situation. We can
conclude that we should avoid adding new values to *readtable-alist*.
This is why I suggest creating new readtable-switching form instead of
(in-readtable).

>Another thing I don't fully understand in your idea (but I did
>reimplement it that way) is why the readtable information has to go on
>every Emacs->Lisp request,
E.g. request can contain (read-from-string), which can occur in proper
readtable context. But frankly, I just copied package-related policy
to readtables without any serious design work :)