* match.c (extract): Check for negative value of opt_nobindings,

which forces the printing.

* txr.c (help): Under -b, mention that printing the  word false is
suppressed also. Added documentation for -B.
(main): Implemented -B option.

* txr.1: Documented -B option and added clarifying text under -b
option explaining the conditions under which bindings are printed.

4 files changed, 33 insertions, 9 deletions

diff --git a/ChangeLog b/ChangeLog
index 8eea6f22..ddfbdabc 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,15 @@
+2012-02-27  Kaz Kylheku  <kaz@kylheku.com>
+
+	* match.c (extract): Check for negative value of opt_nobindings,
+	which forces the printing.
+
+	* txr.c (help): Under -b, mention that printing the  word false is
+	suppressed also. Added documentation for -B.
+	(main): Implemented -B option.
+
+	* txr.1: Documented -B option and added clarifying text under -b
+	option explaining the conditions under which bindings are printed.
+
 2012-02-26  Kaz Kylheku  <kaz@kylheku.com>
 
 	Fix the issue properly, once and for all, of how to determine
diff --git a/match.c b/match.c
index 5dda9602..bf6b82a6 100644
--- a/match.c
+++ b/match.c
@@ -3590,12 +3590,10 @@ int extract(val spec, val files, val predefined_bindings)
                                                    predefined_bindings,
                                                    t, nil)));
 
-  if (!output_produced) {
-    if (!opt_nobindings) {
-      if (bindings) {
-        bindings = nreverse(bindings);
-        dump_bindings(bindings);
-      }
+  if ((!output_produced && opt_nobindings <= 0) || opt_nobindings < 0) {
+    if (bindings) {
+      bindings = nreverse(bindings);
+      dump_bindings(bindings);
     }
 
     if (!success)
diff --git a/txr.1 b/txr.1
index 2307d2f1..7ea141df 100644
--- a/txr.1
+++ b/txr.1
@@ -107,7 +107,15 @@ Suppresses the printing of variable bindings for a successful query, and the
 word .
 IR false
 for a failed query. The program still sets an appropriate
-termination status.
+termination status.  Bindings are implicitly suppressed if the TXR query
+performs an output operation on any file stream other than *stddebug*.
+(Internal streams like string streams do not count as output.)
+
+.IP -B
+Force the printing of variable bindings for a successful query, and the
+word .
+IR false
+for a failed query, even if the program produced output.
 
 .IP "-l or --lisp-bindings"
 Print the variable bindings in Lisp syntax instead of shell syntax.
diff --git a/txr.c b/txr.c
index 9dc083a9..92893ebe 100644
--- a/txr.c
+++ b/txr.c
@@ -90,8 +90,11 @@ static void help(void)
 "-Dvar                  Predefine variable var, with empty string value.\n"
 "-q                     Quiet: don't report errors during query matching.\n"
 "-v                     Verbose: extra logging from matcher.\n"
-"-b                     Don't dump list of bindings.\n"
-"-l                     If dumping bindings, use a Lisp format.\n"
+"-b                     Don't dump list of bindings, or 'false'\n"
+"                       on unsuccessful termination.\n"
+"-B                     Force list of bindings to be dumped, or false\n"
+"                       if termination is unsuccessful.\n"
+"-l                     If dumping bindings, use TXR Lisp format.\n"
 "-d                     Debugger mode.\n"
 "-a num                 Generate array variables up to num-dimensions.\n"
 "                       Default is 1. Additional dimensions are fudged\n"
@@ -329,6 +332,9 @@ int txr_main(int argc, char **argv)
         case 'b':
           opt_nobindings = 1;
           break;
+        case 'B':
+          opt_nobindings = -1;
+          break;
         case 'l':
           opt_lisp_bindings = 1;
           break;