revise [dict append] to make use of common [string cat] engine.

1 files changed, 24 insertions, 6 deletions

diff --git a/generic/tclDictObj.c b/generic/tclDictObj.c
index f99f984..3be968a 100644
--- a/generic/tclDictObj.c
+++ b/generic/tclDictObj.c
@@ -2282,7 +2282,7 @@ DictAppendCmd(
     Tcl_Obj *const *objv)
 {
     Tcl_Obj *dictPtr, *valuePtr, *resultPtr;
-    int i, allocatedDict = 0;
+    int allocatedDict = 0;
 
     if (objc < 3) {
 	Tcl_WrongNumArgs(interp, 1, objv, "dictVarName key ?value ...?");
@@ -2307,15 +2307,33 @@ DictAppendCmd(
 
     if ((objc > 3) || (valuePtr == NULL)) {
 	/* Only go through append activites when something will change. */
+	Tcl_Obj *appendObjPtr = NULL;
 
-	if (valuePtr == NULL) {
+	if (objc > 3) {
+	    /* Something to append */
+
+	    if (objc == 4) {
+		appendObjPtr = objv[3];
+	    } else if (TCL_OK != TclStringCatObjv(interp, objc-3, objv+3,
+		    &appendObjPtr)) {
+		return TCL_ERROR;
+	    }
+	}
+
+	if (appendObjPtr == NULL) {
+	    /* => (objc == 3) => (valuePtr == NULL) */
 	    TclNewObj(valuePtr);
-	} else if (Tcl_IsShared(valuePtr)) {
-	    valuePtr = Tcl_DuplicateObj(valuePtr);
+	} else if (valuePtr == NULL) {
+	    valuePtr = appendObjPtr;
+	    appendObjPtr = NULL;
 	}
 
-	for (i=3 ; i<objc ; i++) {
-	    Tcl_AppendObjToObj(valuePtr, objv[i]);
+	if (appendObjPtr) {
+	    if (Tcl_IsShared(valuePtr)) {
+		valuePtr = Tcl_DuplicateObj(valuePtr);
+	    }
+
+	    Tcl_AppendObjToObj(valuePtr, appendObjPtr);
 	}
 
 	Tcl_DictObjPut(NULL, dictPtr, objv[2], valuePtr);