bug-gnu-emacs
[Top][All Lists]
Advanced

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

bug#15538: 24.3; Incorrect Expansion of Nested Backquote


From: Stefan Monnier
Subject: bug#15538: 24.3; Incorrect Expansion of Nested Backquote
Date: Tue, 08 Oct 2013 00:30:45 -0400
User-agent: Gnus/5.13 (Gnus v5.13) Emacs/24.3.50 (gnu/linux)

> ``(,,@q)
> (\` ((\, r s)))
> ((3 5))                                 ; Incorrect: This should be ((3 5)
> (4 6))

Indeed, it's incorrect, but I think the intention of the current code is
to consider the above expression as invalid, so the error is to return
a value at step 2 (ignoring the second argument `s' to the unquote)
instead of signalling an error.

If you really want that result, you can do

 ``(,@(list ,@q))


> ``(,@,@q)

And here, you'd have to use

  ``(,@(append ,@q))

I installed a patch into trunk which catches the above problems and
signals an error if/when encountering such situations.
Thank you,


        Stefan





reply via email to

[Prev in Thread] Current Thread [Next in Thread]