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| author | Kaz Kylheku <kaz@kylheku.com> | 2017-02-02 19:27:41 -0800 |
|---|---|---|
| committer | Kaz Kylheku <kaz@kylheku.com> | 2017-02-02 19:27:41 -0800 |
| commit | bae1a8b8d040c42df63436b60cd7d751abca9a76 (patch) | |
| tree | fdf6712d66707d9942ef9fcb42b64439e4c628f5 /share | |
| parent | bc50a3a9cf6f779a37d20cdee66270225206318e (diff) | |
| download | txr-bae1a8b8d040c42df63436b60cd7d751abca9a76.tar.gz txr-bae1a8b8d040c42df63436b60cd7d751abca9a76.tar.bz2 txr-bae1a8b8d040c42df63436b60cd7d751abca9a76.zip | |
bugfix: limit depth of Lisp-1 treatment of places.
This underscores why sys:*lisp1* is so hacky and should be
removed. When we obtain the update, clobber or delete expander
of a place which is the argument of a DWIM, requiring Lisp-1
treatment, we bind the sys:*lisp1* special. This alters the
behavior of obtaining an expander for a symbolic place.
Unfortunately, because call-update-expander (and friends)
use sys:expand, all levels of the form are subject to place
expansion with sys:*lisp1* bound to t.
Example:
(set [(car (inc a 2)) 10] "foo")
Here, the (car ...) form is the place operand of the DWIM
operator, and so sys:*lisp1* is set up around getting its
expander. But then, oops, the a in (inc a 2) is also treated
as Lisp-1, wrongly.
These changes band-aid the situation.
* share/txr/stdlib/place.tl (call-udpate-expander,
call-clobber-expander, call-delete-expander): After retrieving
the expander, bind sys:*lisp1* to nil so that its effect does
not spill over into the sys:expand call which we apply to the
expansion; i.e. reset sys:*lisp1* to nil around recursive
expansion so that the Lisp-1 treatment is confined to depth 1.
Diffstat (limited to 'share')
| -rw-r--r-- | share/txr/stdlib/place.tl | 3 |
1 files changed, 3 insertions, 0 deletions
diff --git a/share/txr/stdlib/place.tl b/share/txr/stdlib/place.tl index b4828f95..13bfc258 100644 --- a/share/txr/stdlib/place.tl +++ b/share/txr/stdlib/place.tl @@ -182,6 +182,7 @@ (let* ((place (sys:pl-expand unex-place env)) (expander (get-update-expander place)) (sys:*pl-env* env) + (sys:*lisp1* nil) (expansion [expander getter setter place body]) (expansion-ex (sys:expand expansion env))) (sys:cp-origin expansion-ex place))) @@ -190,6 +191,7 @@ (let* ((place (sys:pl-expand unex-place env)) (expander (get-clobber-expander place)) (sys:*pl-env* env) + (sys:*lisp1* nil) (expansion [expander ssetter place body]) (expansion-ex (sys:expand expansion env))) (sys:cp-origin expansion-ex place))) @@ -198,6 +200,7 @@ (let* ((place (sys:pl-expand unex-place env)) (expander (get-delete-expander place)) (sys:*pl-env* env) + (sys:*lisp1* nil) (expansion [expander deleter place body]) (expansion-ex (sys:expand expansion env))) (sys:cp-origin expansion-ex place)))) |