using (in-readtable) to select a readtable

[73budden .]

Hi!

  My opinion is that two approaches are incompatible. Problem is the
same I have noted before: (in-package) form leads to implicit (and
sometimes unpredictable) change of current readtable in SLIME.
  I think more discussion is required. First I thought I could suggest
a mode switch which alters behaviour of (in-readtable), but it is
implicit and this is bad.
  So second suggestion is the following:
1. Create new form, say (in-readtbl) which changes readtable, but does
not affect *readtable-alist*
2. Create variable, *lock-readtable-alist*. If it is true, error is
signalled on attempt to alter *readtable-alist*
3. Display readtable name on modeline.