New handle* macro, analogous to catch*.

* share/txr/stdlib/except.tl (sys:expand-handle): New
function.
(handle): Use sys:expand-handle to expand arguments. The
previously unused :whole form argument is now put to use,
and correctly captured using :form rather than :whole.
(handle*): New macro.

* txr.1: Documented.

2 files changed, 27 insertions, 5 deletions

diff --git a/share/txr/stdlib/except.tl b/share/txr/stdlib/except.tl
index abba8bdb..0f81e763 100644
--- a/share/txr/stdlib/except.tl
+++ b/share/txr/stdlib/except.tl
@@ -38,8 +38,9 @@
   (let ((catch-syms [mapcar car catch-clauses]))
     ^(sys:catch ,catch-syms ,try-form ,*catch-clauses)))
 
-(defmacro handle (:whole form try-form . handle-clauses)
-  (let* ((exc-sym (gensym))
+(defun sys:expand-handle (form try-form handle-clauses)
+  (let* ((oper (car form))
+         (exc-sym (gensym))
          (exc-args (gensym))
          (syms-fragments (collect-each ((hc handle-clauses))
                           (tree-case hc
@@ -47,8 +48,9 @@
                              (unless (symbolp name)
                                (sys:handle-bad-syntax hc))
                              (list name ^(apply (lambda ,arglist ,*body)
-                                                ,*(if (and (plusp sys:compat)
-                                                           (<= 161 sys:compat))
+                                                ,*(if (or (eq oper 'handle*)
+                                                          (and (plusp sys:compat)
+                                                               (<= 161 sys:compat)))
                                                     ^(,exc-sym))
                                                 ,exc-args)))
                             (else (sys:handle-bad-syntax hc))))))
@@ -59,5 +61,11 @@
                    ,[mapcar car syms-fragments]
                    ,try-form)))
 
+(defmacro handle (:form form try-form . handle-clauses)
+  (sys:expand-handle form try-form handle-clauses))
+
+(defmacro handle* (:form form try-form . handle-clauses)
+  (sys:expand-handle form try-form handle-clauses))
+
 (defmacro ignwarn (. forms)
   ^(handler-bind (lambda (exc-sym arg) (throw 'continue)) (warning) ,*forms))
diff --git a/txr.1 b/txr.1
index 4abfebb1..d21cdbd3 100644
--- a/txr.1
+++ b/txr.1
@@ -33315,10 +33315,12 @@ exception search as if it didn't exist.  When the handler function terminates,
 either via a normal return or a nonlocal control transfer, then the handler is
 re-enabled.
 
-.coNP Macro @ handle
+.coNP Macros @ handle and @ handle*
 .synb
 .mets (handle < try-expression
 .mets \ \  >> {( symbol <> ( arg *) << body-form *)}*)
+.mets (handle* < try-expression
+.mets \ \  >> {( symbol >> ( type-arg << arg *) << body-form *)}*)
 .syne
 .desc
 The
@@ -33370,6 +33372,18 @@ via
 .code return
 or throwing an exception.
 
+The
+.code handle*
+macro is a variant of
+.code handle
+with the following difference: when
+.code handle*
+invokes a clause, it passes the exception symbol as the leftmost argument
+.metn type-arg .
+Then the exception arguments follow. In contrast,
+only the exception arguments are passed to the clauses of
+.codn handle .
+
 .coNP Macro @ with-resources
 .synb
 .mets (with-resources >> ({ sym >> [ init-form <> [ cleanup-form ])}*)