* generic/tclInt.h (Tcl*InterpState): New internal routines

        * generic/tclResult.c (Tcl*InterpState):        TclSaveInterpState,
        TclRestoreInterpState, and TclDiscardInterpState are superior
        replacements for Tcl_(Save|Restore|Discard)Result.  Intent is that
        these routines will be converted to public routines after TIP approval.

        * generic/tclBasic.c (TclEvalObjvInternal):
        * generic/tclDictObj.c (DictUpdateCmd, DictWithCmd):
        * generic/tclIOGT.c (ExecuteCallback):
        * generic/tclTrace.c (Trace*Proc,TclCheck*Traces,TclCallVarTraces):
        Callers of Tcl_*Result updated to call the new routines.  The
        calls were relocated in several cases to perform save/restore
        operations only when needed.

        * generic/tclEvent.c (HandleBgErrors):
        * generic/tclFCmd.c (CopyRenameOneFile):
        Calls to Tcl_*Result that were eliminated because they appeared
        to serve no useful purpose, typically saving/restoring an error
        message, only to throw it away.

9 files changed, 249 insertions, 150 deletions

diff --git a/ChangeLog b/ChangeLog
index 4ef89d5..2dad878 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,25 @@
+2004-10-19  Don Porter  <dgp@users.sourceforge.net>
+
+	* generic/tclInt.h (Tcl*InterpState):		New internal routines
+	* generic/tclResult.c (Tcl*InterpState):	TclSaveInterpState,
+	TclRestoreInterpState, and TclDiscardInterpState are superior
+	replacements for Tcl_(Save|Restore|Discard)Result.  Intent is that
+	these routines will be converted to public routines after TIP approval.
+
+	* generic/tclBasic.c (TclEvalObjvInternal):
+	* generic/tclDictObj.c (DictUpdateCmd, DictWithCmd):
+	* generic/tclIOGT.c (ExecuteCallback):
+	* generic/tclTrace.c (Trace*Proc,TclCheck*Traces,TclCallVarTraces):
+	Callers of Tcl_*Result updated to call the new routines.  The
+	calls were relocated in several cases to perform save/restore
+	operations only when needed.
+
+	* generic/tclEvent.c (HandleBgErrors):
+	* generic/tclFCmd.c (CopyRenameOneFile):
+	Calls to Tcl_*Result that were eliminated because they appeared
+	to serve no useful purpose, typically saving/restoring an error
+	message, only to throw it away.
+
 2004-10-18  Don Porter  <dgp@users.sourceforge.net>
 
 	* generic/tclBasic.c (Tcl_CreateInterp,Tcl_DeleteInterp):
diff --git a/generic/tclBasic.c b/generic/tclBasic.c
index 84b934d..c568e30 100644
--- a/generic/tclBasic.c
+++ b/generic/tclBasic.c
@@ -13,7 +13,7 @@
  * See the file "license.terms" for information on usage and redistribution
  * of this file, and for a DISCLAIMER OF ALL WARRANTIES.
  *
- * RCS: @(#) $Id: tclBasic.c,v 1.128 2004/10/18 21:15:34 dgp Exp $
+ * RCS: @(#) $Id: tclBasic.c,v 1.129 2004/10/19 21:54:06 dgp Exp $
  */
 
 #include "tclInt.h"
@@ -3059,17 +3059,6 @@ TclEvalObjvInternal(interp, objc, objv, command, length, flags)
      * Call 'leave' command traces
      */
     if (!(cmdPtr->flags & CMD_IS_DELETED)) {
-	int saveErrFlags = iPtr->flags & ERR_ALREADY_LOGGED;
-	Tcl_Obj *saveOptions = iPtr->returnOpts;
-	Tcl_Obj *saveErrInfo = iPtr->errorInfo;
-	Tcl_Obj *saveErrCode = iPtr->errorCode;
-	if (saveErrInfo) {
-	    Tcl_IncrRefCount(saveErrInfo);
-	}
-	if (saveErrCode) {
-	    Tcl_IncrRefCount(saveErrCode);
-	}
-	Tcl_IncrRefCount(saveOptions);
         if ((cmdPtr->flags & CMD_HAS_EXEC_TRACES) && (traceCode == TCL_OK)) {
             traceCode = TclCheckExecutionTraces(interp, command, length,
                    cmdPtr, code, TCL_TRACE_LEAVE_EXEC, objc, objv);
@@ -3078,28 +3067,6 @@ TclEvalObjvInternal(interp, objc, objv, command, length, flags)
             traceCode = TclCheckInterpTraces(interp, command, length,
                    cmdPtr, code, TCL_TRACE_LEAVE_EXEC, objc, objv);
         }
-	if (traceCode == TCL_OK) {
-	    Tcl_DecrRefCount(iPtr->returnOpts);
-	    iPtr->returnOpts = saveOptions;
-	    Tcl_IncrRefCount(iPtr->returnOpts);
-	    iPtr->flags |= saveErrFlags;
-	    if (iPtr->errorCode) {
-		Tcl_DecrRefCount(iPtr->errorCode);
-	    }
-	    iPtr->errorCode = saveErrCode;
-	    if (iPtr->errorInfo) {
-		Tcl_DecrRefCount(iPtr->errorInfo);
-	    }
-	    iPtr->errorInfo = saveErrInfo;
-	} else {
-	    if (saveErrCode) {
-		Tcl_DecrRefCount(saveErrCode);
-	    }
-	    if (saveErrInfo) {
-		Tcl_DecrRefCount(saveErrInfo);
-	    }
-	}
-	Tcl_DecrRefCount(saveOptions);
     }
     TclCleanupCommand(cmdPtr);
 
diff --git a/generic/tclDictObj.c b/generic/tclDictObj.c
index 6f78c9c..6d99243 100644
--- a/generic/tclDictObj.c
+++ b/generic/tclDictObj.c
@@ -9,7 +9,7 @@
  * See the file "license.terms" for information on usage and redistribution
  * of this file, and for a DISCLAIMER OF ALL WARRANTIES.
  *
- * RCS: @(#) $Id: tclDictObj.c,v 1.24 2004/10/11 19:58:31 dkf Exp $
+ * RCS: @(#) $Id: tclDictObj.c,v 1.25 2004/10/19 21:54:06 dgp Exp $
  */
 
 #include "tclInt.h"
@@ -2739,7 +2739,7 @@ DictUpdateCmd(interp, objc, objv)
 {
     Tcl_Obj *dictPtr, *objPtr;
     int i, result, dummy, allocdict = 0;
-    Tcl_SavedResult sr;
+    TclInterpState state;
 
     if (objc < 6 || objc & 1) {
 	Tcl_WrongNumArgs(interp, 2, objv,
@@ -2794,9 +2794,9 @@ DictUpdateCmd(interp, objc, objv)
      * Double-check that it is still a dictionary.
      */
 
-    Tcl_SaveResult(interp, &sr);
+    state = TclSaveInterpState(interp, result);
     if (Tcl_DictObjSize(interp, dictPtr, &dummy) != TCL_OK) {
-	Tcl_DiscardResult(&sr);
+	TclDiscardInterpState(state);
 	return TCL_ERROR;
     }
 
@@ -2826,15 +2826,14 @@ DictUpdateCmd(interp, objc, objv)
 
     if (Tcl_ObjSetVar2(interp, objv[2], NULL, dictPtr,
 	    TCL_LEAVE_ERR_MSG) == NULL) {
-	Tcl_DiscardResult(&sr);
+	TclDiscardInterpState(state);
 	if (allocdict) {
 	    TclDecrRefCount(dictPtr);
 	}
 	return TCL_ERROR;
     }
 
-    Tcl_RestoreResult(interp, &sr);
-    return result;
+    return TclRestoreInterpState(interp, state);
 }
 
 /*
@@ -2863,7 +2862,7 @@ DictWithCmd(interp, objc, objv)
 {
     Tcl_Obj *dictPtr, *keysPtr, *keyPtr, *valPtr, **keyv, *leafPtr;
     Tcl_DictSearch s;
-    Tcl_SavedResult sr;
+    TclInterpState state;
     int done, result, keyc, i, allocdict=0;
 
     if (objc < 4) {
@@ -2939,10 +2938,10 @@ DictWithCmd(interp, objc, objv)
      * Double-check that it is still a dictionary.
      */
 
-    Tcl_SaveResult(interp, &sr);
+    state = TclSaveInterpState(interp, result);
     if (Tcl_DictObjSize(interp, dictPtr, &i) != TCL_OK) {
 	TclDecrRefCount(keysPtr);
-	Tcl_DiscardResult(&sr);
+	TclDiscardInterpState(state);
 	return TCL_ERROR;
     }
 
@@ -2968,7 +2967,7 @@ DictWithCmd(interp, objc, objv)
 	    if (allocdict) {
 		TclDecrRefCount(dictPtr);
 	    }
-	    Tcl_DiscardResult(&sr);
+	    TclDiscardInterpState(state);
 	    return TCL_ERROR;
 	}
 	if (leafPtr == DICT_PATH_NON_EXISTENT) {
@@ -2976,7 +2975,7 @@ DictWithCmd(interp, objc, objv)
 	    if (allocdict) {
 		TclDecrRefCount(dictPtr);
 	    }
-	    Tcl_RestoreResult(interp, &sr);
+	    TclRestoreInterpState(interp, state);
 	    return TCL_OK;
 	}
     } else {
@@ -3016,11 +3015,10 @@ DictWithCmd(interp, objc, objv)
 	if (allocdict) {
 	    TclDecrRefCount(dictPtr);
 	}
-	Tcl_DiscardResult(&sr);
+	TclDiscardInterpState(state);
 	return TCL_ERROR;
     }
-    Tcl_RestoreResult(interp, &sr);
-    return result;
+    return TclRestoreInterpState(interp, state);
 }
 
 /*
diff --git a/generic/tclEvent.c b/generic/tclEvent.c
index 5ef1533..9eb195f 100644
--- a/generic/tclEvent.c
+++ b/generic/tclEvent.c
@@ -12,7 +12,7 @@
  * See the file "license.terms" for information on usage and redistribution
  * of this file, and for a DISCLAIMER OF ALL WARRANTIES.
  *
- * RCS: @(#) $Id: tclEvent.c,v 1.48 2004/10/15 04:01:29 dgp Exp $
+ * RCS: @(#) $Id: tclEvent.c,v 1.49 2004/10/19 21:54:06 dgp Exp $
  */
 
 #include "tclInt.h"
@@ -291,11 +291,8 @@ HandleBgErrors(clientData)
              */
 
             if (Tcl_IsSafe(interp)) {
-		Tcl_SavedResult save;
-		
-		Tcl_SaveResult(interp, &save);
+		Tcl_ResetResult(interp);
                 TclObjInvoke(interp, 2, objv, TCL_INVOKE_HIDDEN);
-		Tcl_RestoreResult(interp, &save);
             } else {
 
 		/*
diff --git a/generic/tclFCmd.c b/generic/tclFCmd.c
index 17959fc..a74b6d6 100644
--- a/generic/tclFCmd.c
+++ b/generic/tclFCmd.c
@@ -9,7 +9,7 @@
  * See the file "license.terms" for information on usage and redistribution
  * of this file, and for a DISCLAIMER OF ALL WARRANTIES.
  *
- * RCS: @(#) $Id: tclFCmd.c,v 1.28 2004/10/06 14:59:02 dgp Exp $
+ * RCS: @(#) $Id: tclFCmd.c,v 1.29 2004/10/19 21:54:07 dgp Exp $
  */
 
 #include "tclInt.h"
@@ -642,7 +642,6 @@ CopyRenameOneFile(interp, source, target, copyFlag, force)
 		 * cross-filesystem copy.  We do this through our Tcl
 		 * library.
 		 */
-		Tcl_SavedResult savedResult;
 		Tcl_Obj *copyCommand = Tcl_NewListObj(0,NULL);
 		Tcl_IncrRefCount(copyCommand);
 		Tcl_ListObjAppendElement(interp, copyCommand, 
@@ -656,7 +655,6 @@ CopyRenameOneFile(interp, source, target, copyFlag, force)
 		}
 		Tcl_ListObjAppendElement(interp, copyCommand, source);
 		Tcl_ListObjAppendElement(interp, copyCommand, target);
-		Tcl_SaveResult(interp, &savedResult);
 		result = Tcl_EvalObjEx(interp, copyCommand, 
 				       TCL_EVAL_GLOBAL | TCL_EVAL_DIRECT);
 		Tcl_DecrRefCount(copyCommand);
@@ -666,11 +664,7 @@ CopyRenameOneFile(interp, source, target, copyFlag, force)
 		     * We will pass on the Tcl error message and
 		     * can ensure this by setting errfile to NULL
 		     */
-		    Tcl_DiscardResult(&savedResult);
 		    errfile = NULL;
-		} else {
-		    /* The copy was successful */
-		    Tcl_RestoreResult(interp, &savedResult);
 		}
 	    } else {
 		errfile = errorBuffer;
diff --git a/generic/tclIOGT.c b/generic/tclIOGT.c
index 22e5362..37b57be 100644
--- a/generic/tclIOGT.c
+++ b/generic/tclIOGT.c
@@ -10,7 +10,7 @@
  * See the file "license.terms" for information on usage and redistribution
  * of this file, and for a DISCLAIMER OF ALL WARRANTIES.
  *
- * CVS: $Id: tclIOGT.c,v 1.10 2004/10/06 13:47:34 dkf Exp $
+ * CVS: $Id: tclIOGT.c,v 1.11 2004/10/19 21:54:07 dgp Exp $
  */
 
 #include "tclInt.h"
@@ -383,13 +383,13 @@ ExecuteCallback (dataPtr, interp, op, buf, bufLen, transmit, preserve)
     Tcl_Obj* resObj;		    /* See below, switch (transmit) */
     int resLen;
     unsigned char* resBuf;
-    Tcl_SavedResult ciSave;
+    TclInterpState state = NULL;
     int res = TCL_OK;
     Tcl_Obj* command = Tcl_DuplicateObj (dataPtr->command);
     Tcl_Obj* temp;
 
     if (preserve) {
-	Tcl_SaveResult (dataPtr->interp, &ciSave);
+	state = TclSaveInterpState(dataPtr->interp, res);
     }
 
     if (command == (Tcl_Obj*) NULL) {
@@ -488,14 +488,14 @@ ExecuteCallback (dataPtr, interp, op, buf, bufLen, transmit, preserve)
     Tcl_ResetResult(dataPtr->interp);
 
     if (preserve) {
-	Tcl_RestoreResult(dataPtr->interp, &ciSave);
+	(void) TclRestoreInterpState(dataPtr->interp, state);
     }
 
     return res;
 
     cleanup:
     if (preserve) {
-	Tcl_RestoreResult(dataPtr->interp, &ciSave);
+	(void) TclRestoreInterpState(dataPtr->interp, state);
     }
 
     if (command != (Tcl_Obj*) NULL) {
diff --git a/generic/tclInt.h b/generic/tclInt.h
index 3ffaacc..260e8dc 100644
--- a/generic/tclInt.h
+++ b/generic/tclInt.h
@@ -12,7 +12,7 @@
  * See the file "license.terms" for information on usage and redistribution
  * of this file, and for a DISCLAIMER OF ALL WARRANTIES.
  *
- * RCS: @(#) $Id: tclInt.h,v 1.182 2004/10/18 21:15:41 dgp Exp $
+ * RCS: @(#) $Id: tclInt.h,v 1.183 2004/10/19 21:54:07 dgp Exp $
  */
 
 #ifndef _TCLINT
@@ -1422,6 +1422,8 @@ typedef struct Interp {
 #define SAFE_INTERP			 0x80
 #define INTERP_TRACE_IN_PROGRESS	0x200
 
+typedef struct TclInterpState_ *TclInterpState;
+
 /*
  * Maximum number of levels of nesting permitted in Tcl commands (used
  * to catch infinite recursion).
@@ -1708,6 +1710,8 @@ EXTERN int		TclCheckBadOctal _ANSI_ARGS_((Tcl_Interp *interp,
 			    CONST char *value));
 EXTERN void             TclCleanupLiteralTable _ANSI_ARGS_((
                             Tcl_Interp* interp, LiteralTable* tablePtr ));
+EXTERN void		TclDiscardInterpState _ANSI_ARGS_ ((
+			    TclInterpState state));
 EXTERN void		TclExpandTokenArray _ANSI_ARGS_((
 			    Tcl_Parse *parsePtr));
 EXTERN int		TclFileAttrsCmd _ANSI_ARGS_((Tcl_Interp *interp,
@@ -1904,6 +1908,10 @@ EXTERN VOID             TclRememberJoinableThread _ANSI_ARGS_((Tcl_ThreadId id))
 EXTERN void		TclRememberMutex _ANSI_ARGS_((Tcl_Mutex *mutex));
 EXTERN void		TclRemoveScriptLimitCallbacks _ANSI_ARGS_((
 			    Tcl_Interp *interp));
+EXTERN int		TclRestoreInterpState _ANSI_ARGS_ ((
+			    Tcl_Interp *interp, TclInterpState state));
+EXTERN TclInterpState	TclSaveInterpState _ANSI_ARGS_ ((
+			    Tcl_Interp *interp, int status));
 EXTERN VOID             TclSignalExitThread _ANSI_ARGS_((Tcl_ThreadId id,
 			    int result));
 EXTERN int		TclSubstTokens _ANSI_ARGS_((Tcl_Interp *interp,
diff --git a/generic/tclResult.c b/generic/tclResult.c
index 2545d1f..de474f7 100644
--- a/generic/tclResult.c
+++ b/generic/tclResult.c
@@ -8,7 +8,7 @@
  * See the file "license.terms" for information on usage and redistribution
  * of this file, and for a DISCLAIMER OF ALL WARRANTIES.
  *
- * RCS: @(#) $Id: tclResult.c,v 1.16 2004/10/17 14:22:08 msofer Exp $
+ * RCS: @(#) $Id: tclResult.c,v 1.17 2004/10/19 21:54:07 dgp Exp $
  */
 
 #include "tclInt.h"
@@ -21,6 +21,159 @@ static void             ResetObjResult _ANSI_ARGS_((Interp *iPtr));
 static void		SetupAppendBuffer _ANSI_ARGS_((Interp *iPtr,
 			    int newSpace));
 
+/*
+ *  This structure is used to take a snapshot of the interpreter
+ *  state in TclSaveInterpState.  You can snapshot the state,
+ *  execute a command, and then back up to the result or the
+ *  error that was previously in progress.
+ */
+typedef struct InterpState {
+    int status;			/* return code status */
+    int flags;			/* Each remaining field saves */
+    int returnLevel;		/* the corresponding field of */
+    int returnCode;		/* the Interp struct.  These */
+    Tcl_Obj *errorInfo;		/* fields take together are the */
+    Tcl_Obj *errorCode;		/* "state" of the interp. */
+    Tcl_Obj *returnOpts;
+    Tcl_Obj *objResult;
+} InterpState;
+
+
+/*
+ *----------------------------------------------------------------------
+ *
+ * TclSaveInterpState --
+ *
+ *      Fills a token with a snapshot of the current state of the
+ *      interpreter.  The snapshot can be restored at any point by
+ *      TclRestoreInterpState. 
+ *
+ *      The token returned must be eventally passed to one of the
+ *      routines TclRestoreInterpState or TclDiscardInterpState,
+ *      or there will be a memory leak.
+ *
+ * Results:
+ *	Returns a token representing the interp state.
+ *
+ * Side effects:
+ *	None.
+ *
+ *----------------------------------------------------------------------
+ */
+
+TclInterpState
+TclSaveInterpState(interp, status)
+    Tcl_Interp* interp;     /* Interpreter's state to be saved */
+    int status;             /* status code for current operation */
+{
+    Interp *iPtr = (Interp *)interp;
+    InterpState *statePtr = (InterpState *)ckalloc(sizeof(InterpState));
+
+    statePtr->status = status;
+    statePtr->flags = iPtr->flags & ERR_ALREADY_LOGGED;
+    statePtr->returnLevel = iPtr->returnLevel;
+    statePtr->returnCode = iPtr->returnCode;
+    statePtr->errorInfo = iPtr->errorInfo;
+    if (statePtr->errorInfo) {
+	Tcl_IncrRefCount(statePtr->errorInfo);
+    }
+    statePtr->errorCode = iPtr->errorCode;
+    if (statePtr->errorCode) {
+	Tcl_IncrRefCount(statePtr->errorCode);
+    }
+    statePtr->returnOpts = iPtr->returnOpts;
+    if (statePtr->returnOpts) {
+	Tcl_IncrRefCount(statePtr->returnOpts);
+    }
+    statePtr->objResult = Tcl_GetObjResult(interp);
+    Tcl_IncrRefCount(statePtr->objResult);
+    return (TclInterpState) statePtr;
+}
+
+/*
+ *----------------------------------------------------------------------
+ *
+ * TclRestoreInterpState --
+ *
+ *      Accepts an interp and a token previously returned by
+ *      TclSaveInterpState.  Restore the state of the interp
+ *      to what it was at the time of the TclSaveInterpState call.
+ *
+ * Results:
+ *	Returns the status value originally passed in to TclSaveInterpState.
+ *
+ * Side effects:
+ *	Restores the interp state and frees memory held by token.
+ *
+ *----------------------------------------------------------------------
+ */
+
+int
+TclRestoreInterpState(interp, state)
+    Tcl_Interp* interp;		/* Interpreter's state to be restored*/
+    TclInterpState state;	/* saved interpreter state */
+{
+    Interp *iPtr = (Interp *)interp;
+    InterpState *statePtr = (InterpState *)state;
+    int status = statePtr->status;
+
+    iPtr->flags &= ~ERR_ALREADY_LOGGED;
+    iPtr->flags |= (statePtr->flags & ERR_ALREADY_LOGGED);
+
+    iPtr->returnLevel = statePtr->returnLevel;
+    iPtr->returnCode = statePtr->returnCode;
+    iPtr->errorInfo = statePtr->errorInfo;
+    if (iPtr->errorInfo) {
+	Tcl_IncrRefCount(iPtr->errorInfo);
+    }
+    iPtr->errorCode = statePtr->errorCode;
+    if (iPtr->errorCode) {
+	Tcl_IncrRefCount(iPtr->errorCode);
+    }
+    iPtr->returnOpts = statePtr->returnOpts;
+    if (iPtr->returnOpts) {
+	Tcl_IncrRefCount(iPtr->returnOpts);
+    }
+    Tcl_SetObjResult(interp, statePtr->objResult);
+    TclDiscardInterpState(state);
+    return status;
+}
+
+/*
+ *----------------------------------------------------------------------
+ *
+ * TclDiscardInterpState --
+ *
+ *      Accepts a token previously returned by TclSaveInterpState.
+ *      Frees the memory it uses.
+ *
+ * Results:
+ *	None.
+ *
+ * Side effects:
+ *	Frees memory.
+ *
+ *----------------------------------------------------------------------
+ */
+
+void
+TclDiscardInterpState(state)
+    TclInterpState state;	/* saved interpreter state */
+{
+    InterpState *statePtr = (InterpState *)state;
+
+    if (statePtr->errorInfo) {
+        Tcl_DecrRefCount(statePtr->errorInfo);
+    }
+    if (statePtr->errorCode) {
+        Tcl_DecrRefCount(statePtr->errorCode);
+    }
+    if (statePtr->returnOpts) {
+        Tcl_DecrRefCount(statePtr->returnOpts);
+    }
+    Tcl_DecrRefCount(statePtr->objResult);
+    ckfree((char*) statePtr);
+}
 
 /*
  *----------------------------------------------------------------------
@@ -739,7 +892,7 @@ Tcl_ResetResult(interp)
 	iPtr->errorCode = NULL;
     }
     if (iPtr->errorInfo) {
-	/* Legacy support*/
+	/* Legacy support */
 	Tcl_ObjSetVar2(interp, iPtr->eiVar, NULL,
 		iPtr->errorInfo, TCL_GLOBAL_ONLY);
 	Tcl_DecrRefCount(iPtr->errorInfo);
diff --git a/generic/tclTrace.c b/generic/tclTrace.c
index b2067b3..3d5e835 100644
--- a/generic/tclTrace.c
+++ b/generic/tclTrace.c
@@ -11,7 +11,7 @@
  * See the file "license.terms" for information on usage and redistribution
  * of this file, and for a DISCLAIMER OF ALL WARRANTIES.
  *
- * RCS: @(#) $Id: tclTrace.c,v 1.16 2004/10/15 04:01:33 dgp Exp $
+ * RCS: @(#) $Id: tclTrace.c,v 1.17 2004/10/19 21:54:07 dgp Exp $
  */
 
 #include "tclInt.h"
@@ -1286,9 +1286,6 @@ TraceCommandProc(clientData, interp, oldName, newName, flags)
     int flags;			/* OR-ed bits giving operation and other
 				 * information. */
 {
-    Interp *iPtr = (Interp *) interp;
-    Tcl_Obj *stateReturnOpts;
-    Tcl_SavedResult state;
     TraceCommandInfo *tcmdPtr = (TraceCommandInfo *) clientData;
     int code;
     Tcl_DString cmd;
@@ -1313,38 +1310,23 @@ TraceCommandProc(clientData, interp, oldName, newName, flags)
 	}
 
 	/*
-	 * Execute the command.  Save the interp's result used for the
-	 * command, including the value of iPtr->returnOpts which may be
-	 * modified when Tcl_Eval is invoked. We discard any object
-	 * result the command returns.
+	 * Execute the command.  
+	 * We discard any object result the command returns.
 	 *
 	 * Add the TCL_TRACE_DESTROYED flag to tcmdPtr to indicate to
 	 * other areas that this will be destroyed by us, otherwise a
 	 * double-free might occur depending on what the eval does.
 	 */
 
-	Tcl_SaveResult(interp, &state);
-	stateReturnOpts = iPtr->returnOpts;
-	Tcl_IncrRefCount(stateReturnOpts);
 	if (flags & TCL_TRACE_DESTROYED) {
 	    tcmdPtr->flags |= TCL_TRACE_DESTROYED;
 	}
-
 	code = Tcl_EvalEx(interp, Tcl_DStringValue(&cmd),
 		Tcl_DStringLength(&cmd), 0);
 	if (code != TCL_OK) {	     
 	    /* We ignore errors in these traced commands */
 	    /*** QUESTION: Use Tcl_BackgroundError(interp); instead? ***/
 	}
-
-	Tcl_RestoreResult(interp, &state);
-	if (iPtr->returnOpts != stateReturnOpts) {
-	    Tcl_DecrRefCount(iPtr->returnOpts);
-	    iPtr->returnOpts = stateReturnOpts;
-	    Tcl_IncrRefCount(iPtr->returnOpts);
-	}
-	Tcl_DecrRefCount(stateReturnOpts);
-	
 	Tcl_DStringFree(&cmd);
     }
     /*
@@ -1440,6 +1422,7 @@ TclCheckExecutionTraces(interp, command, numChars, cmdPtr, code,
     int curLevel;
     int traceCode = TCL_OK;
     TraceCommandInfo* tcmdPtr;
+    TclInterpState state = NULL;
     
     if (command == NULL || cmdPtr->tracePtr == NULL) {
 	return traceCode;
@@ -1471,6 +1454,9 @@ TclCheckExecutionTraces(interp, command, numChars, cmdPtr, code,
             tcmdPtr->curFlags = traceFlags | TCL_TRACE_EXEC_DIRECT;
             tcmdPtr->curCode  = code;
 	    tcmdPtr->refCount++;
+	    if (state == NULL) {
+		state = TclSaveInterpState(interp, code);
+	    }
 	    traceCode = TraceExecutionProc((ClientData)tcmdPtr, interp, 
 	          curLevel, command, (Tcl_Command)cmdPtr, objc, objv);
 	    if ((--tcmdPtr->refCount) <= 0) {
@@ -1480,6 +1466,9 @@ TclCheckExecutionTraces(interp, command, numChars, cmdPtr, code,
         lastTracePtr = tracePtr;
     }
     iPtr->activeCmdTracePtr = active.nextPtr;
+    if (state) {
+	(void) TclRestoreInterpState(interp, state);
+    }
     return(traceCode);
 }
 
@@ -1525,6 +1514,7 @@ TclCheckInterpTraces(interp, command, numChars, cmdPtr, code,
     int curLevel;
     int traceCode = TCL_OK;
     TraceCommandInfo* tcmdPtr;
+    TclInterpState state = NULL;
     
     if (command == NULL || iPtr->tracePtr == NULL ||
            (iPtr->flags & INTERP_TRACE_IN_PROGRESS)) {
@@ -1571,6 +1561,9 @@ TclCheckInterpTraces(interp, command, numChars, cmdPtr, code,
 	     */
 	    Tcl_Preserve((ClientData) tracePtr);
 	    tracePtr->flags |= TCL_TRACE_EXEC_IN_PROGRESS;
+	    if (state == NULL) {
+		state = TclSaveInterpState(interp, code);
+	    }
 	    
 	    if (tracePtr->flags & (TCL_TRACE_ENTER_EXEC | TCL_TRACE_LEAVE_EXEC)) {
 	        /* New style trace */
@@ -1603,6 +1596,13 @@ TclCheckInterpTraces(interp, command, numChars, cmdPtr, code,
         lastTracePtr = tracePtr;
     }
     iPtr->activeInterpTracePtr = active.nextPtr;
+    if (state) {
+	if (traceCode == TCL_OK) {
+	    (void) TclRestoreInterpState(interp, state);
+	} else {
+	    TclDiscardInterpState(state);
+	}
+    }
     return(traceCode);
 }
 
@@ -1765,8 +1765,6 @@ TraceExecutionProc(ClientData clientData, Tcl_Interp *interp,
 	 * Second, create the tcl callback, if required.
 	 */
 	if (call) {
-	    Tcl_SavedResult state;
-	    Tcl_Obj *stateReturnOpts;
 	    Tcl_DString cmd;
 	    Tcl_DString sub;
 	    int i;
@@ -1814,16 +1812,10 @@ TraceExecutionProc(ClientData clientData, Tcl_Interp *interp,
 	    }
 	    
 	    /*
-	     * Execute the command.  Save the interp's result used for
-	     * the command, including the value of iPtr->returnOpts which
-	     * may be modified when Tcl_Eval is invoked.  We discard any
-	     * object result the command returns.
+	     * Execute the command.  
+	     * We discard any object result the command returns.
 	     */
 
-	    Tcl_SaveResult(interp, &state);
-	    stateReturnOpts = iPtr->returnOpts;
-	    Tcl_IncrRefCount(stateReturnOpts);
-
 	    tcmdPtr->flags |= TCL_TRACE_EXEC_IN_PROGRESS;
 	    iPtr->flags    |= INTERP_TRACE_IN_PROGRESS;
 	    tcmdPtr->refCount++;
@@ -1838,20 +1830,6 @@ TraceExecutionProc(ClientData clientData, Tcl_Interp *interp,
 	    if (tcmdPtr->flags == 0) {
 		flags |= TCL_TRACE_DESTROYED;
 	    }
-	    
-            if (traceCode == TCL_OK) {
-		/* Restore result if trace execution was successful */
-		Tcl_RestoreResult(interp, &state);
-		if (iPtr->returnOpts != stateReturnOpts) {
-		    Tcl_DecrRefCount(iPtr->returnOpts);
-		    iPtr->returnOpts = stateReturnOpts;
-		    Tcl_IncrRefCount(iPtr->returnOpts);
-		}
-            } else {
-		Tcl_DiscardResult(&state);
-	    }
-	    Tcl_DecrRefCount(stateReturnOpts);
-
 	    Tcl_DStringFree(&cmd);
 	}
 	
@@ -1923,7 +1901,6 @@ TraceVarProc(clientData, interp, name1, name2, flags)
     int flags;			/* OR-ed bits giving operation and other
 				 * information. */
 {
-    Tcl_SavedResult state;
     TraceVarInfo *tvarPtr = (TraceVarInfo *) clientData;
     char *result;
     int code;
@@ -1979,19 +1956,17 @@ TraceVarProc(clientData, interp, name1, name2, flags)
 #endif
 	    
 	    /*
-	     * Execute the command.  Save the interp's result used for
-	     * the command. We discard any object result the command returns.
+	     * Execute the command.  
+	     * We discard any object result the command returns.
 	     *
 	     * Add the TCL_TRACE_DESTROYED flag to tvarPtr to indicate to
 	     * other areas that this will be destroyed by us, otherwise a
 	     * double-free might occur depending on what the eval does.
 	     */
 
-	    Tcl_SaveResult(interp, &state);
 	    if (flags & TCL_TRACE_DESTROYED) {
 		tvarPtr->flags |= TCL_TRACE_DESTROYED;
 	    }
-
 	    code = Tcl_EvalEx(interp, Tcl_DStringValue(&cmd),
 		    Tcl_DStringLength(&cmd), 0);
 	    if (code != TCL_OK) {	     /* copy error msg to result */
@@ -1999,9 +1974,6 @@ TraceVarProc(clientData, interp, name1, name2, flags)
 		Tcl_IncrRefCount(errMsgObj);
 		result = (char *) errMsgObj;
 	    }
-
-	    Tcl_RestoreResult(interp, &state);
-
 	    Tcl_DStringFree(&cmd);
 	}
     }
@@ -2450,16 +2422,7 @@ TclCallVarTraces(iPtr, arrayPtr, varPtr, part1, part2, flags, leaveErrMsg)
     int copiedName;
     int code = TCL_OK;
     int disposeFlags = 0;
-    int saveErrFlags = iPtr->flags & ERR_ALREADY_LOGGED;
-    Tcl_Obj *saveErrInfo = iPtr->errorInfo;
-    Tcl_Obj *saveErrCode = iPtr->errorCode;
-
-    if (saveErrInfo) {
-	Tcl_IncrRefCount(saveErrInfo);
-    }
-    if (saveErrCode) {
-	Tcl_IncrRefCount(saveErrCode);
-    }
+    TclInterpState state = NULL;
 
     /*
      * If there are already similar trace procedures active for the
@@ -2526,6 +2489,9 @@ TclCallVarTraces(iPtr, arrayPtr, varPtr, part1, part2, flags, leaveErrMsg)
 		continue;
 	    }
 	    Tcl_Preserve((ClientData) tracePtr);
+	    if (state == NULL) {
+		state = TclSaveInterpState((Tcl_Interp *)iPtr, code);
+	    }
 	    result = (*tracePtr->traceProc)(tracePtr->clientData,
 		    (Tcl_Interp *) iPtr, part1, part2, flags);
 	    if (result != NULL) {
@@ -2559,6 +2525,9 @@ TclCallVarTraces(iPtr, arrayPtr, varPtr, part1, part2, flags, leaveErrMsg)
 	    continue;
 	}
 	Tcl_Preserve((ClientData) tracePtr);
+	if (state == NULL) {
+	    state = TclSaveInterpState((Tcl_Interp *)iPtr, code);
+	}
 	result = (*tracePtr->traceProc)(tracePtr->clientData,
 		(Tcl_Interp *) iPtr, part1, part2, flags);
 	if (result != NULL) {
@@ -2582,24 +2551,6 @@ TclCallVarTraces(iPtr, arrayPtr, varPtr, part1, part2, flags, leaveErrMsg)
      */
 
     done:
-    if (code == TCL_OK) {
-	iPtr->flags |= saveErrFlags;
-	if (iPtr->errorInfo) {
-	    Tcl_DecrRefCount(iPtr->errorInfo);
-	}
-	iPtr->errorInfo = saveErrInfo;
-	if (iPtr->errorCode) {
-	    Tcl_DecrRefCount(iPtr->errorCode);
-	}
-	iPtr->errorCode = saveErrCode;
-    } else {
-	if (saveErrInfo) {
-	    Tcl_DecrRefCount(saveErrInfo);
-	}
-	if (saveErrCode) {
-	    Tcl_DecrRefCount(saveErrCode);
-	}
-    }
     if (code == TCL_ERROR) {
 	if (leaveErrMsg) {
 	    CONST char *type = "";
@@ -2623,8 +2574,17 @@ TclCallVarTraces(iPtr, arrayPtr, varPtr, part1, part2, flags, leaveErrMsg)
 	    } else {
 		TclVarErrMsg((Tcl_Interp *) iPtr, part1, part2, type, result);
 	    }
+	    TclDiscardInterpState(state);
+	} else {
+	    (void) TclRestoreInterpState((Tcl_Interp *)iPtr, state);
 	}
 	DisposeTraceResult(disposeFlags,result);
+    } else if (state) {
+	if (code == TCL_OK) {
+	    code = TclRestoreInterpState((Tcl_Interp *)iPtr, state);
+	} else {
+	    TclDiscardInterpState(state);
+	}
     }
 
     if (arrayPtr != NULL) {