From 35378dda85c1757b86ddf28e763fc37111e54c48 Mon Sep 17 00:00:00 2001 From: Kaz Kylheku Date: Tue, 20 Dec 2016 11:04:30 -0800 Subject: doc: document place expander hashes. * txr.1: Document *place-update-expander*, *place-clobber-expander* and *place-delete-expander*. --- txr.1 | 17 +++++++++++++++++ 1 file changed, 17 insertions(+) diff --git a/txr.1 b/txr.1 index 4ae879cd..6f8021b7 100644 --- a/txr.1 +++ b/txr.1 @@ -30400,6 +30400,23 @@ treat the situation in a satisfactory way using a definition, which effectively then supplies inline code whenever a certain form is used as a place, and that code itself is treated as a place. +.coNP Special variables @, *place-update-expander* @ *place-clobber-expander* and @ *place-delete-expander* +.desc +These variables hold hash tables, by means of which update expanders, +clobber expanders and delete expanders are registered, as associations +between symbols and functions. + +If +.code "[*place-update-expander* 'sym]" +yields a function, then symbol +.code sym +is the basis for a syntactic place. If the expression yields +.codn nil , +then forms beginning with +.code sym +are not syntactic places. (The situation of a clobber accessor or delete +accessor being defined without an update expander is improper). + .SS* Quasiquote Operator Syntax .coNP Macro @ qquote .synb -- cgit v1.2.3