Index: generic/predefined.xotcl
===================================================================
diff -u -rf0f0b5422a37c8d05f6b835de37fda6bb7347dfd -rdaafc0f0261f6b47a01c7cc8975acdd66f91f360
--- generic/predefined.xotcl	(.../predefined.xotcl)	(revision f0f0b5422a37c8d05f6b835de37fda6bb7347dfd)
+++ generic/predefined.xotcl	(.../predefined.xotcl)	(revision daafc0f0261f6b47a01c7cc8975acdd66f91f360)
@@ -42,7 +42,7 @@
   #
   foreach cmd [info command ::nx::core::cmd::Object::*] {
     set cmdName [namespace tail $cmd]
-    if {$cmdName in [list "instvar"]} continue
+    if {$cmdName in [list "exists" "instvar"]} continue
     ::nx::core::alias Object $cmdName $cmd 
   }
   
@@ -445,9 +445,11 @@
     return ${slotParent}::$name
   }
 
-  ::nx::MetaSlot method createFromParameterSyntax {target -per-object:switch 
-						      {-initblock ""} 
-						      value default:optional} {
+  ::nx::MetaSlot method createFromParameterSyntax {
+    target -per-object:switch 
+    {-initblock ""} 
+    value default:optional
+  } {
     set opts [list]
     set colonPos [string first : $value]
     if {$colonPos == -1} {
@@ -518,7 +520,7 @@
   
   # use low level interface for defining slot values. Normally, this is
   # done via slot objects, which are defined later.
-  
+
   proc createBootstrapAttributeSlots {class definitions} {
     foreach att $definitions {
       if {[llength $att]>1} {foreach {att default} $att break}
@@ -541,7 +543,7 @@
 
         # checking subclasses is not required during bootstrap
         foreach i [::nx::core::cmd::ClassInfo::instances $class] {
-          if {![$i exists $att]} {
+          if {![::nx::core::existsvar $i $att]} {
             if {[string match {*\[*\]*} $default]} {
               set value [::nx::core::dispatch $i -objscope ::eval subst $default]
             } else {
@@ -557,8 +559,7 @@
     #puts stderr "Bootstrapslot for $class calls __invalidateobjectparameter"
     $class __invalidateobjectparameter
   }
-  
-  
+
   ############################################
   # Define slots for slots
   ############################################
@@ -619,6 +620,7 @@
   #
   # If set to {{{true}}}, the accessor methods are registered with the
   # domain object scope only. It defaults to {{{false}}}.
+
   createBootstrapAttributeSlots ::nx::ObjectParameterSlot {
     {name "[namespace tail [::nx::core::current object]]"}
     {methodname}
@@ -639,7 +641,7 @@
     if {![set :multivalued]} {
       error "Property $prop of [set :domain]->$obj ist not multivalued"
     }
-    if {[$obj exists $prop]} {
+    if {[::nx::core::existsvar $obj $prop]} {
       ::nx::core::setvar $obj $prop [linsert [::nx::core::setvar $obj $prop] $pos $value]
     } else {
       ::nx::core::setvar $obj $prop [list $value]
@@ -692,7 +694,7 @@
           ${:methodname}
     }
   }
-  
+
   #################################################################
   # We have no working objectparameter yet, since it requires a
   # minimal slot infrastructure to build object parameters from
@@ -775,7 +777,8 @@
     #puts stderr "[::nx::core::current method] ${name} returns [list oparam $objparamdefinition mparam $methodparamdefinition]"
     return [list oparam $objparamdefinition mparam $methodparamdefinition]
   }
-   
+
+  
   proc ::nx::core::parametersFromSlots {obj} {
     set parameterdefinitions [list]
     foreach slot [::nx::objectInfo slotobjects $obj] {
@@ -789,7 +792,7 @@
     }
     return $parameterdefinitions
   }
-  
+
   # @method ::nx::Object#objectparameter
   ::nx::Object protected method objectparameter {{lastparameter __initcmd:initcmd,optional}} {
     #puts stderr "... objectparameter [::nx::core::current object]"
@@ -804,8 +807,8 @@
     #puts stderr "*** parameter definition for [::nx::core::current object]: $parameterdefinitions"
     return $parameterdefinitions
   }
-  
 
+
   ############################################
   #  RelationSlot
   ############################################
@@ -852,7 +855,7 @@
       error "$value is not a $prop of $obj (valid are: $old)"
     }
   }
-  
+ 
   ::nx::RelationSlot public method delete {-nocomplain:switch obj prop value} {
     #puts stderr RelationSlot-delete-[::nx::core::current args]
     $obj $prop [:delete_value $obj $prop [$obj info $prop] $value]
@@ -861,6 +864,7 @@
   ::nx::RelationSlot public method get {obj prop} {
     ::nx::core::relation $obj $prop
   }
+
   ::nx::RelationSlot public method add {obj prop value {pos 0}} {
     if {![set :multivalued]} {
       error "Property $prop of ${:domain}->$obj ist not multivalued"
@@ -872,8 +876,8 @@
   ::nx::RelationSlot public method delete {-nocomplain:switch obj prop value} {
     uplevel [list ::nx::core::relation $obj $prop [:delete_value $obj $prop [::nx::core::relation $obj $prop] $value]]
   }
-  
-  
+
+ 
   ############################################
   # system slots
   ############################################
@@ -951,16 +955,18 @@
     ::nx::RelationSlot create ${os}::Class::slot::object-mixin 
     ::nx::RelationSlot create ${os}::Class::slot::object-filter -elementtype ""
   }
+
   ::nx::core::register_system_slots ::nx
   proc ::nx::core::register_system_slots {} {}
+
   
   ############################################
   # Attribute slots
   ############################################
   ::nx::MetaSlot __invalidateobjectparameter
   
   # @object ::nx::Attribute
-  #
+
   # Attribute slots are used to manage the access, mutation, and
   # querying of instance variables. There is a helper method {{@method
   # ::nx::Object class attribute}} to define the attributes of classes
@@ -982,7 +988,7 @@
   # @param arg
   # @superclass ::nx::doc::entities::object::nx::ObjectParameterSlot
   ::nx::MetaSlot create ::nx::Attribute -superclass ::nx::ObjectParameterSlot
-  
+
   createBootstrapAttributeSlots ::nx::Attribute {
     {value_check once}
     incremental
@@ -1010,11 +1016,11 @@
     ::nx::core::next ;# do first ordinary slot initialization
     # there might be already default values registered on the class
     set __initcmd ""
-    if {[:exists default]} {
-    } elseif [:exists initcmd] {
+    if {[info exists :default]} {
+    } elseif [info exists :initcmd] {
       append __initcmd ":trace add variable [list ${:name}] read \
 	\[list [::nx::core::current object] __default_from_cmd \[::nx::core::current object\] [list [set :initcmd]]\]\n"
-    } elseif [:exists valuecmd] {
+    } elseif [info exists :valuecmd] {
       append __initcmd ":trace add variable [list ${:name}] read \
 	\[list [::nx::core::current object] __value_from_cmd \[::nx::core::current object\] [list [set :valuecmd]]\]"
     }
@@ -1039,7 +1045,7 @@
 
       }
     }
-    if {[:exists valuechangedcmd]} {
+    if {[info exists :valuechangedcmd]} {
       append __initcmd ":trace add variable [list ${:name}] write \
 	\[list [::nx::core::current object] __value_changed_cmd \[::nx::core::current object\] [list [set :valuechangedcmd]]\]"
     }