Bugfix: *args* not bound for command line expressions.

The documentation says that *args* is bound to nil,
but actually it is not bound at all.

Let us fix this by actualy binding *args* to the
remaining arguments, and by also allowing
modification of *args* to dynamically take effect.

* txr.c: Set up value of *args* prior to processing
any option which evaluates TXR Lisp. Afterwards,
reload the argument list from that variable.

* txr.1: Documented semantics of *args* during
command line processing.

2 files changed, 21 insertions, 10 deletions

diff --git a/txr.1 b/txr.1
index 0c8108fe..cfcc1925 100644
--- a/txr.1
+++ b/txr.1
@@ -30397,16 +30397,22 @@ The
 variable holds the original, complete list of arguments passed
 from the operating system.
 
-Note: the
+The
 .code *args*
-variable is
-.code nil
-during the processing of the command line,
-so \*(TL expressions invoked using the
-.code -p
-or
+variable is available to to \*(TL expressions invoked from the
+command line via the
+.codn -p ,
 .code -e
-option cannot use it.
+and other such options. During these evaluations,
+.code *args*
+holds all the remaining options, after the invoking option and its
+argument expression. In other words, code executed from the command line
+has access to the remaining arguments which follow it.
+Furthermore, this code may modify the value of
+.codn *args* .
+Such a modification is visible to the option processing code.
+That is to say code executed from the command line can rewrite the remaining
+list of arguments, and that list takes effect.
 
 .coNP Function @ env
 .synb
diff --git a/txr.c b/txr.c
index af8f4bbe..cbd2ff8f 100644
--- a/txr.c
+++ b/txr.c
@@ -398,6 +398,7 @@ int txr_main(int argc, char **argv)
   val parse_stream = std_input;
   val txr_lisp_p = nil;
   val enter_repl = nil;
+  val args_s = intern(lit("*args*"), user_package);
   val self_path_s = intern(lit("self-path"), user_package);
   list_collect_decl(arg_list, arg_tail);
 
@@ -553,7 +554,6 @@ 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))
     {
@@ -583,10 +583,13 @@ int txr_main(int argc, char **argv)
         break;
       case 'e':
         reg_varl(self_path_s, lit("cmdline-expr"));
+        reg_var(args_s, arg_list);
+
         eval_intrinsic(lisp_parse(arg, std_error, colon_k,
                                   lit("cmdline-expr"), colon_k),
                        make_env(bindings, nil, nil));
         evaled = t;
+        arg_list = cdr(lookup_global_var(args_s));
         break;
       case 'p':
       case 'P':
@@ -598,10 +601,12 @@ int txr_main(int argc, char **argv)
                                                 pprinl,
                                                 tprint));
           reg_varl(self_path_s, lit("cmdline-expr"));
+          reg_var(args_s, arg_list);
           pf(eval_intrinsic(lisp_parse(arg, std_error, colon_k,
                                        lit("cmdline-expr"), colon_k),
                             make_env(bindings, nil, nil)), std_output);
           evaled = t;
+          arg_list = cdr(lookup_global_var(args_s));
         }
         break;
       }
@@ -718,7 +723,7 @@ int txr_main(int argc, char **argv)
     }
   }
 
-  reg_var(intern(lit("*args*"), user_package), arg_list);
+  reg_var(args_s, arg_list);
   reg_varl(intern(lit("self-path"), user_package), spec_file_str);
 
   if (!txr_lisp_p)