Re: About `setf' with macro call

[Tassilo Horn <tsdh@gnu.org>]

Stefan Monnier <monnier@iro.umontreal.ca> writes:

> ELISP> (macroexpand '(setf (wrong-order A B) 17))
>> (let*
>>     ((v B)
>>      (v A))
>>   (aset v v 17))
>> --8<---------------cut here---------------end--------------->8---
>
>> Now that explains the let* in the backtrace, but the setf-expansion
>> looks totally wrong!  v is set to B (the index) and then overridden by A
>> (the array).
>
> Actually, no: try (setq print-gensym t) to see the full story.

Argh, it's not the first time I've fallen into that trap.  It happens so
rarely that at the Nth time I've usually forgotten about the N-1th time
and its explanation. ;-)

So now I've eventually put

  (setq print-gensym t
        print-circle t)

in my ~/.emacs, so hopefully I won't be caught another time.

Thanks,
Tassilo