--- a/src/file-io.cc	Fri Nov 05 07:02:36 1999 +0000
+++ b/src/file-io.cc	Fri Nov 05 08:11:59 1999 +0000
@@ -94,12 +94,6 @@
   octave_stream_list::clear ();
 }
 
-static void
-gripe_invalid_file_id (const char *fcn)
-{
-  ::error ("%s: invalid file id", fcn);
-}
-
 static int
 fopen_mode_to_ios_mode (const string& mode)
 {
@@ -161,12 +155,8 @@
   int nargin = args.length ();
 
   if (nargin == 1)
-    {
-      retval = static_cast<double> (octave_stream_list::remove (args(0)));
-
-      if (retval < 0)
-	gripe_invalid_file_id ("fclose");
-    }
+    retval = static_cast<double> (octave_stream_list::remove (args(0),
+				  "fclose"));
   else
     print_usage ("fclose");
 
@@ -194,12 +184,10 @@
 	}
       else
 	{
-	  octave_stream os = octave_stream_list::lookup (fid);
+	  octave_stream os = octave_stream_list::lookup (fid, "fflush");
 
-	  if (os.is_valid ())
+	  if (! error_state)
 	    retval = static_cast<double> (os.flush ());
-	  else
-	    gripe_invalid_file_id ("fflush");
 	}
     }
   else
@@ -222,9 +210,9 @@
 
   if (nargin == 1 || nargin == 2)
     {
-      octave_stream os = octave_stream_list::lookup (args(0));
+      octave_stream os = octave_stream_list::lookup (args(0), "fgetl");
 
-      if (os.is_valid ())
+      if (! error_state)
 	{
 	  octave_value len_arg = (nargin == 2)
 	    ? args(1) : octave_value (static_cast<double> (INT_MAX));
@@ -239,8 +227,6 @@
 	      retval(0) = tmp;
 	    }
 	}
-      else
-	gripe_invalid_file_id ("fgetl");
     }
   else
     print_usage ("fgetl");
@@ -262,9 +248,9 @@
 
   if (nargin == 1 || nargin == 2)
     {
-      octave_stream os = octave_stream_list::lookup (args(0));
+      octave_stream os = octave_stream_list::lookup (args(0), "fgets");
 
-      if (os.is_valid ())
+      if (! error_state)
 	{
 	  octave_value len_arg = (nargin == 2)
 	    ? args(1) : octave_value (static_cast<double> (INT_MAX));
@@ -279,8 +265,6 @@
 	      retval(0) = tmp;
 	    }
 	}
-      else
-	gripe_invalid_file_id ("fgets");
     }
   else
     print_usage ("fgets");
@@ -472,12 +456,10 @@
 
   if (nargin == 1)
     {
-      octave_stream os = octave_stream_list::lookup (args(0));
+      octave_stream os = octave_stream_list::lookup (args(0), "frewind");
 
-      if (os.is_valid ())
+      if (! error_state)
 	retval = static_cast<double> (os.rewind ());
-      else
-	gripe_invalid_file_id ("frewind");
     }
   else
     print_usage ("frewind");
@@ -502,17 +484,15 @@
 
   if (nargin == 2 || nargin == 3)
     {
-      octave_stream os = octave_stream_list::lookup (args(0));
+      octave_stream os = octave_stream_list::lookup (args(0), "fseek");
 
-      if (os.is_valid ())
+      if (! error_state)
 	{
 	  octave_value origin_arg = (nargin == 3)
 	    ? args(2) : octave_value (-1.0);
 
 	  retval = static_cast<double> (os.seek (args(1), origin_arg));
 	}
-      else
-	::error ("fseek: invalid file id");
     }
   else
     print_usage ("fseek");
@@ -529,12 +509,10 @@
 
   if (nargin == 1)
     {
-      octave_stream os = octave_stream_list::lookup (args(0));
+      octave_stream os = octave_stream_list::lookup (args(0), "ftell");
 
-      if (os.is_valid ())
+      if (! error_state)
 	retval = static_cast<double> (os.tell ());
-      else
-	gripe_invalid_file_id ("ftell");
     }
   else
     print_usage ("ftell");
@@ -555,14 +533,14 @@
       int fmt_n = 0;
 
       if (args(0).is_string ())
-	os = octave_stream_list::lookup (1);
+	os = octave_stream_list::lookup (1, "fprintf");
       else
 	{
 	  fmt_n = 1;
-	  os = octave_stream_list::lookup (args(0));
+	  os = octave_stream_list::lookup (args(0), "fprintf");
 	}
 
-      if (os.is_valid ())
+      if (! error_state)
 	{
 	  if (args(fmt_n).is_string ())
 	    {
@@ -583,8 +561,6 @@
 	  else
 	    ::error ("fprintf: format must be a string");
 	}
-      else
-	gripe_invalid_file_id ("fprintf");
     }
   else
     print_usage ("fprintf");
@@ -601,12 +577,10 @@
 
   if (nargin == 2)
     {
-      octave_stream os = octave_stream_list::lookup (args(0));
+      octave_stream os = octave_stream_list::lookup (args(0), "fputs");
 
-      if (os.is_valid ())
+      if (! error_state)
 	retval = os.puts (args(1));
-      else
-	gripe_invalid_file_id ("fputs");
     }
   else
     print_usage ("fputs");
@@ -692,9 +666,9 @@
 
   if (nargin == 3 && args(2).is_string ())
     {
-      octave_stream os = octave_stream_list::lookup (args(0));
+      octave_stream os = octave_stream_list::lookup (args(0), "fscanf");
 
-      if (os.is_valid ())
+      if (! error_state)
 	{
 	  if (args(1).is_string ())
 	    {
@@ -705,8 +679,6 @@
 	  else
 	    ::error ("fscanf: format must be a string");
 	}
-      else
-	gripe_invalid_file_id ("fscanf");
     }
   else
     {
@@ -715,9 +687,9 @@
 
       if (nargin == 2 || nargin == 3)
 	{
-	  octave_stream os = octave_stream_list::lookup (args(0));
+	  octave_stream os = octave_stream_list::lookup (args(0), "fscanf");
 
-	  if (os.is_valid ())
+	  if (error_state)
 	    {
 	      if (args(1).is_string ())
 		{
@@ -739,8 +711,6 @@
 	      else
 		::error ("fscanf: format must be a string");
 	    }
-	  else
-	    gripe_invalid_file_id ("fscanf");
 	}
       else
 	print_usage ("fscanf");
@@ -983,9 +953,9 @@
       retval(1) = -1.0;
       retval(0) = Matrix ();
 
-      octave_stream os = octave_stream_list::lookup (args(0));
+      octave_stream os = octave_stream_list::lookup (args(0), "fread");
 
-      if (os.is_valid ())
+      if (! error_state)
 	{
 	  octave_value size = (nargin > 1)
 	    ? args(1) : octave_value (octave_Inf);
@@ -1006,8 +976,6 @@
 	  retval(1) = static_cast<double> (count);
 	  retval(0) = tmp;
 	}
-      else
-	gripe_invalid_file_id ("fread");
     }
   else
     print_usage ("fread");
@@ -1111,9 +1079,9 @@
 
   if (nargin > 1 && nargin < 6)
     {
-      octave_stream os = octave_stream_list::lookup (args(0));
+      octave_stream os = octave_stream_list::lookup (args(0), "fwrite");
 
-      if (os.is_valid ())
+      if (! error_state)
 	{
 	  octave_value data = args(1);
 
@@ -1130,8 +1098,6 @@
 
 	  retval = status;
 	}
-      else
-	gripe_invalid_file_id ("fwrite");
     }
   else
     print_usage ("fwrite");
@@ -1151,12 +1117,10 @@
 
   if (nargin == 1)
     {
-      octave_stream os = octave_stream_list::lookup (args(0));
+      octave_stream os = octave_stream_list::lookup (args(0), "feof");
 
-      if (os.is_valid ())
+      if (! error_state)
 	retval = os.eof () ? 1.0 : 0.0;
-      else
-	gripe_invalid_file_id ("feof");
     }
   else
     print_usage ("feof");
@@ -1176,9 +1140,9 @@
 
   if (nargin == 1 || nargin == 2)
     {
-      octave_stream os = octave_stream_list::lookup (args(0));
+      octave_stream os = octave_stream_list::lookup (args(0), "ferror");
 
-      if (os.is_valid ())
+      if (! error_state)
 	{
 	  bool clear = false;
 
@@ -1199,8 +1163,6 @@
 	  retval(1) = static_cast<double> (error_number);
 	  retval(0) = error_message;
 	}
-      else
-	gripe_invalid_file_id ("ferror");
     }
   else
     print_usage ("ferror");
@@ -1294,12 +1256,8 @@
   int nargin = args.length ();
 
   if (nargin == 1)
-    {
-      retval = static_cast<double> (octave_stream_list::remove (args(0)));
-
-      if (retval < 0)
-	gripe_invalid_file_id ("pclose");
-    }
+    retval = static_cast<double> (octave_stream_list::remove (args(0),
+				  "pclose"));
   else
     print_usage ("pclose");