From 7037b38fa7d2c26a371877770ffcf81e107f3b42 Mon Sep 17 00:00:00 2001
From: Vitor Santos Costa <vsc@dcc.fc.up.pt>
Date: Sun, 28 Feb 2010 00:57:29 +0000
Subject: [PATCH] make nb_ undefined variable return an error, as SWI does.

---
 C/errors.c      | 15 +++++++++++++++
 C/globals.c     | 16 ++++++++++++----
 H/Yap.h         |  1 +
 pl/boot.yap     |  2 ++
 pl/messages.yap |  2 ++
 5 files changed, 32 insertions(+), 4 deletions(-)

diff --git a/C/errors.c b/C/errors.c
index bf4c34857..3d6c857bb 100644
--- a/C/errors.c
+++ b/C/errors.c
@@ -902,6 +902,21 @@ Yap_Error(yap_error_number type, Term where, char *format,...)
       serious = TRUE;
     }
     break;
+  case EXISTENCE_ERROR_VARIABLE:
+    {
+      int i;
+      Term ti[2];
+
+      i = strlen(tmpbuf);
+      ti[0] = MkAtomTerm(AtomVariable);
+      ti[1] = where;
+      nt[0] = Yap_MkApplTerm(FunctorExistenceError, 2, ti);
+      tp = tmpbuf+i;
+      psize -= i;
+      fun = FunctorError;
+      serious = TRUE;
+    }
+    break;
   case EVALUATION_ERROR_FLOAT_OVERFLOW:
     {
       int i;
diff --git a/C/globals.c b/C/globals.c
index f1c79ccdc..cefa30833 100644
--- a/C/globals.c
+++ b/C/globals.c
@@ -1285,8 +1285,10 @@ p_nb_getval(void)
     return FALSE;
   }
   ge = FindGlobalEntry(AtomOfTerm(t));
-  if (!ge)
+  if (!ge) {
+    Yap_Error(EXISTENCE_ERROR_VARIABLE,t,"nb_getval");
     return FALSE;
+  }
   READ_LOCK(ge->GRWLock);
   to = ge->global;
   if (IsVarTerm(to) && IsUnboundVar(VarOfTerm(to))) {
@@ -1309,8 +1311,10 @@ nbdelete(Atom at)
   Prop gp, g0;
 
   ge = FindGlobalEntry(at);
-  if (!ge)
+  if (!ge) {
+    Yap_Error(EXISTENCE_ERROR_VARIABLE,MkAtomTerm(at),"nb_delete");
     return FALSE;
+  }
   WRITE_LOCK(ge->GRWLock);
   ae = ge->AtomOfGE;
   if (GlobalVariables == ge) {
@@ -1375,8 +1379,10 @@ p_nb_create(void)
     return FALSE;
   }
   ge = GetGlobalEntry(AtomOfTerm(t));
-  if (!ge)
+  if (!ge) {
+    Yap_Error(EXISTENCE_ERROR_VARIABLE,t,"nb_create");
     return FALSE;
+  }
   if (IsVarTerm(tarity)) {
     Yap_Error(INSTANTIATION_ERROR,tarity,"nb_create");
     return FALSE;
@@ -1418,8 +1424,10 @@ p_nb_create2(void)
     return FALSE;
   }
   ge = GetGlobalEntry(AtomOfTerm(t));
-  if (!ge)
+  if (!ge) {
+    Yap_Error(EXISTENCE_ERROR_VARIABLE,t,"nb_create");
     return FALSE;
+  }
   if (IsVarTerm(tarity)) {
     Yap_Error(INSTANTIATION_ERROR,tarity,"nb_create");
     return FALSE;
diff --git a/H/Yap.h b/H/Yap.h
index c3d104992..f8870dd2d 100644
--- a/H/Yap.h
+++ b/H/Yap.h
@@ -464,6 +464,7 @@ typedef enum
   EXISTENCE_ERROR_KEY,
   EXISTENCE_ERROR_SOURCE_SINK,
   EXISTENCE_ERROR_STREAM,
+  EXISTENCE_ERROR_VARIABLE,
   INSTANTIATION_ERROR,
   INTERRUPT_ERROR,
   OPERATING_SYSTEM_ERROR,
diff --git a/pl/boot.yap b/pl/boot.yap
index d805300d1..74e78bc8c 100755
--- a/pl/boot.yap
+++ b/pl/boot.yap
@@ -75,6 +75,8 @@ true :- true.
 	nb_setval('$open_expands_filename',true),
 	'$debug_on'(false),
 	nb_setval('$trace',off),
+	nb_setval('$assert_all',off),
+	nb_setval('$if_skip_mode',no_skip),
 	b_setval('$spy_glist',[]),
 	% simple trick to find out if this is we are booting from Prolog.
 	get_value('$user_module',V),
diff --git a/pl/messages.yap b/pl/messages.yap
index 6024d6dee..85fd9df4a 100644
--- a/pl/messages.yap
+++ b/pl/messages.yap
@@ -166,6 +166,8 @@ system_message(error(existence_error(key,Key), Where)) -->
 	[ 'EXISTENCE ERROR- ~w: ~w not an existing key' - [Where,Key] ].
 system_message(error(existence_error(thread,Thread), Where)) -->
 	[ 'EXISTENCE ERROR- ~w: ~w not a running thread' - [Where,Thread] ].
+system_message(error(existence_error(variable,Var), Where)) -->
+	[ 'EXISTENCE ERROR- ~w: variable ~w does not exist' - [Where,Var] ].
 system_message(error(existence_error(Name,F), W)) -->
 	{ object_name(Name, ObjName) },
 	[ 'EXISTENCE ERROR- ~w could not open ~a ~w' - [W,ObjName,F] ].