Namespace *dummy;
    const char *name;
    int code;

    linkPtr = (Link *) Tcl_VarTraceInfo2(interp, varName, NULL,
	    TCL_GLOBAL_ONLY, LinkTraceProc, NULL);
    if (linkPtr != NULL) {
	Tcl_SetObjResult(interp, Tcl_ObjPrintf(
		"variable '%s' is already linked", varName));
	return TCL_ERROR;
    }

    linkPtr = (Link *)Tcl_Alloc(sizeof(Link));
    linkPtr->interp = interp;
    linkPtr->nsPtr = NULL;
    linkPtr->varName = Tcl_NewStringObj(varName, -1);