From d11481b8cd38d63d21d50fb1b7fc9c49a7f21c0d Mon Sep 17 00:00:00 2001
From: Kaz Kylheku <kaz@kylheku.com>
Date: Fri, 23 Sep 2011 14:49:00 -0700
Subject: * match.c, parser.y: Support for old output syntax removed. Leading
 :nothrow with trailing material is an error now.

* txr.1: Updated. Made note of errors in pipes being asynchronous.
---
 ChangeLog |  7 +++++++
 match.c   | 32 ++++++++++++++------------------
 parser.y  |  5 +++--
 txr.1     | 18 ++++++------------
 4 files changed, 30 insertions(+), 32 deletions(-)

diff --git a/ChangeLog b/ChangeLog
index f625f46b..facb6c99 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,10 @@
+2011-09-23  Kaz Kylheku  <kaz@kylheku.com>
+
+	* match.c, parser.y: Support for old output syntax removed.
+	Leading :nothrow with trailing material is an error now.
+
+	* txr.1: Updated. Made note of errors in pipes being asynchronous.
+
 2011-09-23  Kaz Kylheku  <kaz@kylheku.com>
 
 	* tests/002/query-1.txr: Old next syntax rewritten to new.
diff --git a/match.c b/match.c
index dd30f72f..f5a35870 100644
--- a/match.c
+++ b/match.c
@@ -1408,29 +1408,25 @@ repeat_spec_same_data:
         goto repeat_spec_same_data;
       } else if (sym == output_s) {
         val specs = second(first_spec);
-        val old_style_dest = third(first_spec);
-        val new_style_dest = fourth(first_spec);
-        val nt = nil;
+        val dest_spec = third(first_spec);
+        val nothrow = nil;
         val dest;
         fpip_t fp;
 
-        if (old_style_dest) {
-          dest = cat_str(subst_vars(old_style_dest, bindings), nil);
+        if (eq(first(dest_spec), nothrow_k)) {
+          if (rest(dest_spec))
+            sem_error(spec_linenum, lit("material after :nothrow in output"), nao);
+          dest = string(L"-");
         } else {
-          if (eq(first(new_style_dest), nothrow_k))
-            push(nil, &new_style_dest);
+          val form = first(dest_spec);
+          val val = eval_form(form, bindings);
 
-          {
-            val form = first(new_style_dest);
-            val val = eval_form(form, bindings);
-
-            if (!val)
-              sem_error(spec_linenum,
-                        lit("output: unbound variable in form ~a"), form, nao);
+          if (!val)
+            sem_error(spec_linenum,
+                      lit("output: unbound variable in form ~a"), form, nao);
 
-            nt = eq(second(new_style_dest), nothrow_k);
-            dest = or2(cdr(val), string(L"-"));
-          }
+          nothrow = eq(second(dest_spec), nothrow_k);
+          dest = or2(cdr(val), string(L"-"));
         }
 
         fp = (errno = 0, complex_open(dest, t));
@@ -1438,7 +1434,7 @@ repeat_spec_same_data:
         debugf(lit("opening data sink ~a"), dest, nao);
 
         if (complex_open_failed(fp)) {
-          if (nt) {
+          if (nothrow) {
             debugf(lit("could not open ~a: "
                        "treating as failed match due to nothrow"), dest, nao);
             return nil;
diff --git a/parser.y b/parser.y
index 98d299f3..7fb277af 100644
--- a/parser.y
+++ b/parser.y
@@ -267,13 +267,14 @@ catch_clauses_opt : CATCH ')' newl
 
 output_clause : OUTPUT ')' o_elems '\n'
                 out_clauses
-                END newl        { $$ = list(output_s, $5, $3, nao); }
+                END newl        { $$ = nil;
+                                  yyerror("obsolete output syntax: trailing material"); }
               | OUTPUT ')' newl
                 out_clauses
                 END newl        { $$ = list(output_s, $4, nao); }
               | OUTPUT exprs ')' newl
                 out_clauses
-                END newl        { $$ = list(output_s, $5, nil, $2, nao); }
+                END newl        { $$ = list(output_s, $5, $2, nao); }
               | OUTPUT exprs ')' o_elems '\n'
                 out_clauses
                 END newl        { $$ = nil;
diff --git a/txr.1 b/txr.1
index 78b109cd..82d128e3 100644
--- a/txr.1
+++ b/txr.1
@@ -2280,27 +2280,21 @@ The syntax of the @(output) directive is:
   .
   @(end)
 
-An obsolescent syntax is also supported:
-
-  @(output)...optional destination...
-  .
-  . one or more output directives or lines
-  .
-  @(end)
-
 The optional destination is a filename, the special name, - which
 redirects to standard output, or a shell command preceded by the ! symbol.
 In the first form, the destination may be specified as a variable
 which holds text, a string literal or a quasiliteral
 
-In the second obsolescent form, the material to the right of @(output)
-is query text which may contain variables.
-
-The new syntax throws an exception if the output destination
+The syntax throws an exception if the output destination
 cannot be opened, unless the :nothrow keyword is present, in which
 case the situation is treated as a match failure.  The old syntax throws an
 exception.
 
+Note that since command pipes are processes that report errors
+asynchronously, a failing command will not throw an immediate exception that
+can be suppressed with :nothrow.   This is for synchronous errors, like
+trying to open a destination file, but not having permissions, etc.
+
 .SS Output Text
 
 Text in an output clause is not matched against anything, but is output
-- 
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