Hello,
I cannot find a standard way to figure out whether a setf expander has been defined for a symbol FOO (via either DEFSETF or DEFINE-SETF-EXPANDER).
Is there one? Otherwise, I would also be happy with an SBCL-only solution.
Thank you !
On Oct 8, 2012, at 15:28 , Didier Verna didier@lrde.epita.fr wrote:
Hello,
I cannot find a standard way to figure out whether a setf expander has been defined for a symbol FOO (via either DEFSETF or DEFINE-SETF-EXPANDER).
Is there one? Otherwise, I would also be happy with an SBCL-only solution.
Thank you !
#'get-setf-expansion, perhaps?
Raymond Wiker rwiker@gmail.com wrote:
#'get-setf-expansion, perhaps?
Nope, because it gives you something by default.
CL-USER> (get-setf-expansion '(not-previously-defined)) NIL NIL (#:NEW886) (FUNCALL #'(SETF NOT-PREVIOUSLY-DEFINED) #:NEW886) (NOT-PREVIOUSLY-DEFINED)
Just guessing: If you see that the writer form is a funcall to a setf function, you can then check with fboundp if such a function actually exists. This is probably a bit shaky, but maybe good enough for practical purposes?
Pascal
On 8 Oct 2012, at 16:56, Didier Verna didier@lrde.epita.fr wrote:
Raymond Wiker rwiker@gmail.com wrote:
#'get-setf-expansion, perhaps?
Nope, because it gives you something by default.
CL-USER> (get-setf-expansion '(not-previously-defined)) NIL NIL (#:NEW886) (FUNCALL #'(SETF NOT-PREVIOUSLY-DEFINED) #:NEW886) (NOT-PREVIOUSLY-DEFINED)
-- Resistance is futile. You will be jazzimilated.
Scientific site: http://www.lrde.epita.fr/~didier Music (Jazz) site: http://www.didierverna.com
pro mailing list pro@common-lisp.net http://lists.common-lisp.net/cgi-bin/mailman/listinfo/pro
-- Pascal Costanza
Pascal Costanza wrote:
Just guessing: If you see that the writer form is a funcall to a setf function, you can then check with fboundp if such a function actually exists. This is probably a bit shaky, but maybe good enough for practical purposes?
Good idea. To be more precise:
- if the writer form is something else than (FUNCALL #'(SETF FOO) ...) then there is a defsetf going on (it even takes precedence over a potential setf function).
- if the writer form is (FUNCALL #'(SETF FOO) ...) and that function is bound, then there is a setf function going on but no defsetf.
- otherwise, there is no writer at all.
I think this might just work.
On Mon, 08 Oct 2012 17:38:42 +0200, Didier Verna said:
Pascal Costanza wrote:
Just guessing: If you see that the writer form is a funcall to a setf function, you can then check with fboundp if such a function actually exists. This is probably a bit shaky, but maybe good enough for practical purposes?
Good idea. To be more precise:
if the writer form is something else than (FUNCALL #'(SETF FOO) ...) then there is a defsetf going on (it even takes precedence over a potential setf function).
if the writer form is (FUNCALL #'(SETF FOO) ...) and that function is bound, then there is a setf function going on but no defsetf.
otherwise, there is no writer at all.
I think this might just work.
As Pascal said, it's a bit shaky. E.g. a user could define
(defsetf foo (x) (y) `(funcall #'(setf foo) ,y ,x))
which gives a false negative.
Also, it won't be portable, because the (FUNCALL #'(SETF FOO) ...) form isn't required (the standard just specifies something with the same effect as it).
IMO, you will have to see what's done by each implementation, and use implementation specific, perhaps even internal functions to get that information.
This would be a good subject for a CDR, to provide a public introspective API.
On Oct 9, 2012, at 07:52 , Pascal J. Bourguignon wrote:
IMO, you will have to see what's done by each implementation, and use implementation specific, perhaps even internal functions to get that information.
This would be a good subject for a CDR, to provide a public introspective API.
I second that. A "side" CDR would be to specify other "function specifiers" beside (SETF FOO).
Cheers -- MA
-- __Pascal Bourguignon__
On 08/10/2012, at 15:28, Didier Verna didier@lrde.epita.fr wrote:
Hello,
I cannot find a standard way to figure out whether a setf expander has been defined for a symbol FOO (via either DEFSETF or DEFINE-SETF-EXPANDER).
Is there one? Otherwise, I would also be happy with an SBCL-only solution.
Thank you !
-- Resistance is futile. You will be jazzimilated.
Scientific site: http://www.lrde.epita.fr/~didier Music (Jazz) site: http://www.didierverna.com
pro mailing list pro@common-lisp.net http://lists.common-lisp.net/cgi-bin/mailman/listinfo/pro
pro mailing list pro@common-lisp.net http://lists.common-lisp.net/cgi-bin/mailman/listinfo/pro
-- Marco Antoniotti, Associate Professor tel. +39 - 02 64 48 79 01 DISCo, Università Milano Bicocca U14 2043 http://bimib.disco.unimib.it Viale Sarca 336 I-20126 Milan (MI) ITALY
Please note that I am not checking my Spam-box anymore. Please do not forward this email without asking me first.
-
Didier Verna -
Marco Antoniotti -
Martin Simmons -
Pascal Costanza -
Pascal J. Bourguignon -
Raymond Wiker