using (in-readtable) to select a readtable

[Attila Lendvai]

>   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.


why would it be unpredictable? if there's a relevant entry in
*readtable-alist*, then it changes the current readtable only in the
dynamic extent of an operation (as opposed to e.g. globally, or in the
dynamic extent of the REPL, or sumesuch).

i don't see the problem: compile-toplevel-form and friends look for an
in-package form higher up in the buffer, does the usual dance which
includes optionally rebinding whatever *readtable-alist* says as the
current readtable. then the same is done for an in-readtable form,
which may rebind another readtable and thus override
*readtable-alist*. and then the whole thing is forgotten when the
compilation is finished and the stack is unwound.

IOW, the two can live next to each other independently, in-readtable
having priority over *readtable-alist*.

or am i missing something?


>   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.


IMO, this is way too much unjustified complexity (or i'm missing something).

-- 
• attila lendvai
• PGP: 963F 5D5F 45C7 DFCD 0A39
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