From d613cde8a2579f8e40248dc3839c39c89de4009e Mon Sep 17 00:00:00 2001
From: Kaz Kylheku <kaz@kylheku.com>
Date: Sun, 20 Nov 2016 21:31:51 -0800
Subject: Revive -b option for binding Lisp variables.

* txr.c (txr_main): Implement -b option that takes an
argument. Ensure that -b produces an error if clumped with
other options.

* txr.1: Documented -b var=val.
---
 txr.1 | 30 ++++++++++++++++++++++++------
 txr.c | 24 +++++++++++++++++++++---
 2 files changed, 45 insertions(+), 9 deletions(-)

diff --git a/txr.1 b/txr.1
index 8e1d2dca..c7d408e1 100644
--- a/txr.1
+++ b/txr.1
@@ -482,12 +482,30 @@ of this function.
 Verbose operation. Detailed logging is enabled.
 
 .coIP -b
-This is a deprecated option, which is silently ignored. In \*(TX versions
-prior to 90, the printing of variable bindings (see
-.code -B
-option) was
-implicit behavior which was automatically suppressed in certain situations.
-The -b option suppressed it unconditionally.
+This option binds a Lisp global lexical variable (as if by the
+.code defparml
+function) to an object described by Lisp syntax. It requires an argument
+of the form
+.meta sym=value
+where
+.code sym
+must be, syntactically, a token denoting a bindable symbol, and
+.meta value
+is arbitrary \*(TL syntax. The
+.meta sym
+syntax is converted to the symbol it denotes, which is bound as a global
+lexical variable, if it is not already a variable.
+The
+.meta value
+syntax is parsed to the Lisp object it denotes. This object is not subject
+to evaluation; the object itself is stored into the variable binding denoted
+by
+.metn sym .
+Note that if
+.meta sym
+already exists as a global variable, then it is simply overwritten. If
+.meta sym
+is marked special, then it stays special.
 
 .coIP -B
 If the query is successful, print the variable bindings as a sequence
diff --git a/txr.c b/txr.c
index c31c7fa2..9bc3d5fe 100644
--- a/txr.c
+++ b/txr.c
@@ -728,7 +728,7 @@ int txr_main(int argc, char **argv)
     }
 
     /* Single letter options with args: non-clumping. */
-    if (length(arg) == two && find(ref(arg, one), lit("acfepPtC"), nil, nil))
+    if (length(arg) == two && find(ref(arg, one), lit("abcfepPtC"), nil, nil))
     {
       val opt = chr_str(arg, one);
 
@@ -749,6 +749,25 @@ int txr_main(int argc, char **argv)
         if (!do_fixnum_opt(compat, opt, arg))
           return EXIT_FAILURE;
         break;
+      case 'b':
+        drop_privilege();
+        {
+          val pair = partition_star(arg, pos(chr('='), arg, nil, nil));
+          val sym = lisp_parse(pop(&pair), std_error,
+                               colon_k, lit("cmdline-expr"), colon_k);
+          val obj = lisp_parse(pop(&pair), std_error,
+                               colon_k, lit("cmdline-expr"), colon_k);
+
+          if (!bindable(sym)) {
+            format(std_error,
+                   lit("~a: ~s isn't a bindable symbol\n"),
+                   prog_string, sym, nao);
+            return EXIT_FAILURE;
+          }
+
+          reg_var(sym, obj);
+        }
+        break;
       case 'c':
         if (txr_lisp_p) {
           format(std_error,
@@ -827,8 +846,6 @@ int txr_main(int argc, char **argv)
         case 'q':
           match_loglevel = 0;
           break;
-        case 'b': /* deprecated */
-          break;
         case 'B':
           opt_print_bindings = 1;
           break;
@@ -861,6 +878,7 @@ int txr_main(int argc, char **argv)
           stream_set_prop(std_input, real_time_k, nil);
           break;
         case 'a':
+        case 'b':
         case 'c':
         case 'e':
         case 'p':
-- 
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