namespace eval ::xotcl {
  #
  # By setting the variable bootstrap, we can check later, whether we
  # are in bootstrapping mode
  #
  set bootstrap 1
}

#
# First create the ::xotcl2 object system. 
#

namespace eval xotcl2 {
  namespace path ::xotcl
  ::xotcl::createobjectsystem ::xotcl2::Object ::xotcl2::Class

  # provide the standard command set for ::xotcl2::Object
  foreach cmd [info command ::xotcl::cmd::Object::*] {
    set cmdName [namespace tail $cmd]
    if {$cmdName in [list "instvar"]} continue
    ::xotcl::alias Object $cmdName $cmd 
  }
  
  # provide some Tcl-commands as methods for ::xotcl2::Object
  #foreach cmd {array append eval incr lappend set subst unset trace} {
  #  ::xotcl::alias Object $cmd -objscope ::$cmd
  #}
  ::xotcl::alias Object eval -nonleaf ::eval

  # provide the standard command set for Class
  foreach cmd [info command ::xotcl::cmd::Class::*] {
    set cmdName [namespace tail $cmd]
    ::xotcl::alias Class $cmdName $cmd 
  }

  # set a few aliases as protected
  foreach cmd [list __next cleanup  noinit residualargs uplevel upvar] {
    ::xotcl::methodproperty Object $cmd protected 1
  }
  foreach cmd [list recreate] {
    ::xotcl::methodproperty Class $cmd protected 1
  }
  # TODO: info methods shows finally "slots" and "slot". Wanted?

  # protect some methods against redefinition
  ::xotcl::methodproperty Object destroy redefine-protected true
  ::xotcl::methodproperty Class  alloc   redefine-protected true
  ::xotcl::methodproperty Class  dealloc redefine-protected true
  ::xotcl::methodproperty Class  create  redefine-protected true
  
  # define method "method" for Class and Object
  ::xotcl::method Class method {
    name arguments body -precondition -postcondition
  } {
    set conditions [list]
    if {[info exists precondition]}  {lappend conditions -precondition  $precondition}
    if {[info exists postcondition]} {lappend conditions -postcondition $postcondition}
    ::xotcl::method [self] $name $arguments $body {*}$conditions
  }

  ::xotcl::method Object method {
    name arguments body -precondition -postcondition
  } {
    set conditions [list]
    if {[info exists precondition]}  {lappend conditions -precondition  $precondition}
    if {[info exists postcondition]} {lappend conditions -postcondition $postcondition}
    ::xotcl::method [self] -per-object $name $arguments $body {*}$conditions
  }

  # define method modifiers "object", "public" and "protected"
  Class eval {

    # method-modifier for object specific methos
    :method object {what args} {
      if {$what in [list "alias" "forward" "method" "setter"]} {
        return [::xotcl::dispatch [self] ::xotcl::classes::xotcl2::Object::$what {*}$args]
      }
      if {$what in [list "info"]} {
        return [::xotcl2::objectInfo [lindex $args 0] [self] {*}[lrange $args 1 end]]
      }
      if {$what in [list "filter" "mixin"]} {
        return [:object-$what {*}$args]
      }
      if {$what in [list "filterguard" "mixinguard"]} {
        return [::xotcl::dispatch [self] ::xotcl::cmd::Object::$what {*}$args]
      }
    }

    # define unknown handler for class
    :method unknown {m args} {
      error "Method '$m' unknown for [self].\
	Consider '[self] create $m $args' instead of '[self] $m $args'"
    }
    # protected is not jet defined
    ::xotcl::methodproperty [self] unknown protected 1
  }


  Object eval {

    # method modifier "public"
    :method public {args} {
      set p [lsearch -regexp $args {^(method|alias|forward|setter)$}]
      if {$p == -1} {error "$args is not a method defining method"}
      set r [{*}:$args]
      ::xotcl::methodproperty [self] $r protected false
      return $r
    }

    # method modifier "protected"
    :method protected {args} {
      set p [lsearch -regexp $args {^(method|alias|forward|setter)$}]
      if {$p == -1} {error "$args is not a method defining command"}
      set r [{*}:$args]
      ::xotcl::methodproperty [self] $r [self proc] true
      return $r
    }

    # unknown handler for Object
    :protected method unknown {m args} {
      if {![self isnext]} {
        error "[self]: unable to dispatch method '$m'"
      }
    }
    
    # "init" must exist on Object. per default it is empty.
    :protected method init args {}

    # this method is called on calls to object without a specified method
    :protected method defaultmethod {} {::xotcl::self}

    # provide a placeholder for the bootup process. The real definition
    # is based on slots, which are not available at this point.
    :protected method objectparameter {} {;}
  }

  # define forward methods
  ::xotcl::forward Object forward ::xotcl::forward %self -per-object
  ::xotcl::forward Class  forward ::xotcl::forward %self

  # The method __unknown is called in cases, where we try to resolve
  # an unkown class. one could define a custom resolver with this name
  # to load the class on the fly. After the call to __unknown, XOTcl
  # tries to resolve the class again. This meachnism is used e.g. by
  # the ::ttrace mechanism for partial loading by Zoran.
  #
  Class protected object method __unknown {name} {}

  # Add alias methods. cmdName for XOTcl method can be added via
  #   [... info method name <methodName>]
  #
  Object public method alias {-objscope:switch methodName cmd} {
    ::xotcl::alias [self] -per-object $methodName \
        {*}[expr {${objscope} ? "-objscope" : ""}] \
        $cmd
  }
  Class public method alias {-objscope:switch methodName cmd} {
    ::xotcl::alias [self] $methodName \
        {*}[expr {${objscope} ? "-objscope" : ""}] \
        $cmd
  }

  # Add setter methods. 
  #  
  Object public method setter {methodName value:optional} {
    if {[info exists value]} {
      ::xotcl::setter [self] -per-object $methodName $value
    } else {
      ::xotcl::setter [self] -per-object $methodName
    }
  }
  Class public method setter {methodName value:optional} {
    if {[info exists value]} {
      ::xotcl::setter [self] $methodName $value
    } else {
      ::xotcl::setter [self] $methodName
    }
  }

  ########################
  # Info definition
  ########################
  Object create ::xotcl2::objectInfo
  Object create ::xotcl2::classInfo

  #
  # It would be nice to do here "objectInfo configure {alias ..}", but
  # we have no working objectparameter yet due to bootstrapping
  #
  objectInfo eval {
    :alias is ::xotcl::is

    # info info
    :public method info {obj} {
      set methods [list]
      foreach name [::xotcl::cmd::ObjectInfo::methods [self]] {
        if {$name eq "unknown"} continue
        lappend methods $name
      }
      return "valid options are: [join [lsort $methods] {, }]"
    }

    :method unknown {method obj args} {
      error "[::xotcl::self] unknown info option \"$method\"; [$obj info info]"
    }
  }

  classInfo eval {
    :public method mixinof {obj -closure:switch {-scope all} pattern:optional} {
      # scope eq "all" or "object" returns objects, scope eq "class" returns classes
      set withClosure [expr {$closure ? "-closure" : ""}]
      set withPattern [expr {[info exists pattern] ? $pattern : ""}]
      if {$scope eq "all"} {
        set r [::xotcl::cmd::ClassInfo::object-mixin-of $obj {*}$withClosure {*}$withPattern]
        foreach c [::xotcl::cmd::ClassInfo::class-mixin-of $obj {*}$withClosure] {
          lappend r {*}[$c info instances {*}$withPattern]
        }
        return [lsort -unique $r]
      } else {
        return [::xotcl::cmd::ClassInfo::$scope-mixin-of $obj {*}$withClosure {*}$withPattern]
      }
    }
    :alias is ::xotcl::is
    :alias classparent ::xotcl::cmd::ObjectInfo::parent
    :alias classchildren ::xotcl::cmd::ObjectInfo::children
    :alias info [::xotcl::cmd::ObjectInfo::method objectInfo name info]
    :alias unknown [::xotcl::cmd::ObjectInfo::method objectInfo name info]
  }

  foreach cmd [info command ::xotcl::cmd::ObjectInfo::*] {
    ::xotcl::alias ::xotcl2::objectInfo [namespace tail $cmd] $cmd
    ::xotcl::alias ::xotcl2::classInfo [namespace tail $cmd] $cmd
  }
  foreach cmd [info command ::xotcl::cmd::ClassInfo::*] {
    set cmdName [namespace tail $cmd]
    if {$cmdName in [list "object-mixin-of" "class-mixin-of"]} continue
    ::xotcl::alias ::xotcl2::classInfo $cmdName $cmd
  }
  unset cmd

  # register method "info" on Object and Class
  Object forward info -onerror ::xotcl::infoError ::xotcl2::objectInfo %1 {%@2 %self}
  Class forward  info -onerror ::xotcl::infoError ::xotcl2::classInfo %1 {%@2 %self}

  proc ::xotcl::infoError msg {
    #puts stderr "INFO ERROR: <$msg>\n$::errorInfo"
    regsub -all " <object>" $msg "" msg
    regsub -all " <class>" $msg "" msg
    regsub {\"} $msg "\"info " msg
    error $msg ""
  }
  
  #
  # definition of "abstract method foo ...."
  #
  Object method abstract {methtype -per-object:switch methname arglist} {
    if {$methtype ne "method"} {
      error "invalid method type '$methtype', must be 'method'"
    }
    set body "
      if {!\[::xotcl::self isnextcall\]} {
        error \"Abstract method $methname $arglist called\"
      } else {::xotcl::next}
    "
    if {${per-object}} {
      :method -per-object $methname $arglist $body
    }  else {
      :method $methname $arglist $body
    }
  }

  #
  # exit handlers
  #
  proc ::xotcl::unsetExitHandler {} {
    proc ::xotcl::__exitHandler {} {
      # clients should append exit handlers to this proc body
    }
  }
  proc ::xotcl::setExitHandler {newbody} {::proc ::xotcl::__exitHandler {} $newbody}
  proc ::xotcl::getExitHandler {} {::info body ::xotcl::__exitHandler}
  # initialize exit handler
  ::xotcl::unsetExitHandler
 
  namespace export Object Class
}


########################################
# Slot definitions
########################################
#
# We are still in bootstrap code; we cannot use slots/parameter to
# define slots, so the code is a little low level. After the defintion
# of the slots, we can use slot-based code such as "-parameter" or
# "objectparameter".
#
::xotcl2::Class create ::xotcl::MetaSlot
::xotcl::relation ::xotcl::MetaSlot superclass ::xotcl2::Class

::xotcl::MetaSlot public method new args {
  set slotobject [::xotcl::self callingobject]::slot
  if {![::xotcl::is $slotobject object]} {::xotcls::Object create $slotobject}
  eval next -childof $slotobject $args
}

::xotcl::MetaSlot create ::xotcl::Slot
# We have no working objectparameter yet. So invalidate MetaSlot to
# avoid caching.
::xotcl::MetaSlot __invalidateobjectparameter

#foreach o {::xotcl::MetaSlot ::xotcl2::Slot} {
#  foreach r {object class metaclass} {
#    puts stderr "$o $r=[::xotcl::is $o $r]"
#  }
#}

# Provide the a slot based mechanism for building an object
# configuration interface from slot definitions
proc ::xotcl::parameterFromSlot {slot name} {
  set parameterdefinition $name
  set opts [list]
  if {[$slot exists required] && [$slot required]} {
    lappend opts required
  }
  if {[$slot exists type]} {
    lappend opts [$slot type]
  }
  if {[$slot exists arg]} {
    lappend opts arg=[$slot arg]
  }
  if {[$slot exists default]} {
    set arg [::xotcl::setinstvar $slot default]
    # deactivated for now: || [string first {$} $arg] > -1
    if {[string match {*\[*\]*} $arg]} {
      lappend opts substdefault
    }
  } elseif {[$slot exists initcmd]} {
    set arg [::xotcl::setinstvar $slot initcmd]
    lappend opts initcmd
  } 
  if {[$slot exists methodname]} {
    set methodname [::xotcl::setinstvar $slot methodname]
    if {$methodname ne $name} {
      lappend opts arg=$methodname
    }
  }
  if {[llength $opts] > 0} {
    append parameterdefinition :[join $opts ,]
  }
  if {[info exists arg]} {
    lappend parameterdefinition $arg
  }
  return $parameterdefinition
}

proc ::xotcl::parametersFromSlots {obj} {
  set parameterdefinitions [list]
  set slots [::xotcl2::objectInfo slotobjects $obj]
  foreach slot $slots {
    # skip some lots for xotcl1; TODO: maybe different parameterFromSlots for xotcl1?
    if {[::xotcl::is $obj type ::xotcl::Object] && 
        ([$slot name] eq "mixin" || [$slot name] eq "filter")
      } continue
    set name [namespace tail $slot]
    lappend parameterdefinitions -[::xotcl::parameterFromSlot $slot $name]
  }
  return $parameterdefinitions
}

::xotcl2::Object protected method objectparameter {} {
  set parameterdefinitions [::xotcl::parametersFromSlots [self]]
  if {[::xotcl::is [self] class]} {
    lappend parameterdefinitions -parameter:method,optional
  }
  lappend parameterdefinitions \
      -noinit:method,optional,noarg \
      -volatile:method,optional,noarg \
      arg:initcmd,optional
  # for the time being, use:
  #lappend parameterdefinitions args
  #puts stderr "*** parameter definition for [self]: $parameterdefinitions"
  return $parameterdefinitions
}

#
# create class and object for nonpositional argument processing
::xotcl2::Class create ::xotcl2::ParameterType
foreach cmd [info command ::xotcl::cmd::ParameterType::*] {
  ::xotcl::alias ::xotcl2::ParameterType [namespace tail $cmd] $cmd
}

# create an object for dispatching
::xotcl2::ParameterType create ::xotcl2::parameterType


# use low level interface for defining slot values. Normally, this is
# done via slot objects, which are defined later.

proc createBootstrapAttributeSlots {class definitions} {
  if {![::xotcl::is ${class}::slot object]} {
    ::xotcl2::Object create ${class}::slot
  }
  foreach att $definitions {
    if {[llength $att]>1} {foreach {att default} $att break}
    ::xotcl::Slot create ${class}::slot::$att
    if {[info exists default]} {
      ::xotcl::setinstvar ${class}::slot::$att default $default
      unset default
    }
    ::xotcl::setter $class $att
  }

  # do a second round to ensure that the already defined objects
  # have the appropriate default values
  foreach att $definitions {
    if {[llength $att]>1} {foreach {att default} $att break}
    if {[info exists default]} {
      # checking subclasses is not required during bootstrap
      # todo: do we really need $class twice?
      foreach i [::xotcl::cmd::ClassInfo::instances $class] {
	if {![$i exists $att]} {
	  if {[string match {*[*]*} $default]} {
            #set default [$i eval subst $default]
            set default [::xotcl::dispatch $i -objscope ::eval subst $default]
          }
	  ::xotcl::setinstvar $i $att $default
	}
      }
      unset default
    }
  }
  #puts stderr "Bootstrapslot for $class calls __invalidateobjectparameter"
  $class __invalidateobjectparameter
}


############################################
# Define slots for slots
############################################
createBootstrapAttributeSlots ::xotcl::Slot {
  {name "[namespace tail [::xotcl::self]]"}
  {methodname}
  {domain "[lindex [regexp -inline {^(.*)::slot::[^:]+$} [::xotcl::self]] 1]"}
  {defaultmethods {get assign}}
  {manager "[::xotcl::self]"}
  {multivalued false}
  {per-object false}
  {forward-per-object}
  {required false}
  default
  type
}
# maybe add the following slots at some later time here
#   initcmd
#   valuecmd
#   valuechangedcmd

::xotcl::alias ::xotcl::Slot get ::xotcl::setinstvar
::xotcl::alias ::xotcl::Slot assign ::xotcl::setinstvar

::xotcl::Slot public method add {obj prop value {pos 0}} {
  if {![set :multivalued]} {
    error "Property $prop of [set :domain]->$obj ist not multivalued"
  }
  if {[$obj exists $prop]} {
    ::xotcl::setinstvar $obj $prop [linsert [::xotcl::setinstvar $obj $prop] $pos $value]
  } else {
    ::xotcl::setinstvar $obj $prop [list $value]
  }
}
::xotcl::Slot public method delete {-nocomplain:switch obj prop value} {
  set old [::xotcl::setinstvar $obj $prop]
  set p [lsearch -glob $old $value]
  if {$p>-1} {::xotcl::setinstvar $obj $prop [lreplace $old $p $p]} else {
    error "$value is not a $prop of $obj (valid are: $old)"
  }
}

::xotcl::Slot method unknown {method args} {
  set methods [list]
  foreach m [:info callable] {
    if {[::xotcl2::Object info callable $m] ne ""} continue
    if {[string match __* $m]} continue
    lappend methods $m
  }
  error "Method '$method' unknown for slot [::xotcl::self]; valid are: {[lsort $methods]]}"
}

::xotcl::Slot public method destroy {} {
  if {${:domain} ne "" && [::xotcl::is ${:domain} object]} {
    ${:domain} __invalidateobjectparameter
  }
  next
}

::xotcl::Slot method init {args} {
  if {${:domain} eq ""} {
    set :domain [::xotcl::self callingobject]
  }
  if {${:domain} ne ""} {
    if {![info exists :methodname]} {
      set :methodname ${:name}
    }
    ${:domain} __invalidateobjectparameter
    set cl [expr {${:per-object} ? "Object" : "Class"}]
    # since the domain object might be xotcl1 or xotcl2, use dispatch
    ::xotcl::forward ${:domain} ${:name} \
        ${:manager} \
        [list %1 [${:manager} defaultmethods]] %self \
        ${:methodname}
  }
}

############################################
#  InfoSlot
############################################
::xotcl::MetaSlot create ::xotcl::InfoSlot
createBootstrapAttributeSlots ::xotcl::InfoSlot {
  {multivalued true}
  {elementtype ::xotcl2::Class}
}
::xotcl::relation ::xotcl::InfoSlot superclass ::xotcl::Slot
::xotcl::InfoSlot public method get {obj prop} {
    $obj info $prop
}
::xotcl::InfoSlot public method add {obj prop value {pos 0}} {
  if {![set :multivalued]} {
    error "Property $prop of ${:domain}->$obj ist not multivalued"
  }
  #puts stderr "adding infoslot: $obj $prop [linsert [$obj info $prop] $pos $value]"
  $obj $prop [linsert [$obj info $prop] $pos $value]
}
::xotcl::InfoSlot protected method delete_value {obj prop old value} {
  if {[string first * $value] > -1 || [string first \[ $value] > -1} {
    # string contains meta characters
    if {${:elementtype} ne "" && ![string match ::* $value]} {
      # prefix string with ::, since all object names have leading ::
      set value ::$value
    }
    return [lsearch -all -not -glob -inline $old $value]
  } elseif {${:elementtype} ne ""} {
    if {[string first :: $value] == -1} {
      if {![::xotcl::is $value object]} {
	error "$value does not appear to be an object"
      }
      set value [::xotcl::dispatch $value -objscope ::xotcl::self]
    }
    if {![::xotcl::is ${:elementtype} class]} {
      error "$value does not appear to be of type ${:elementtype}"
    }
  }
  set p [lsearch -exact $old $value]
  if {$p > -1} {
    return [lreplace $old $p $p]
  } else {
    error "$value is not a $prop of $obj (valid are: $old)"
  }
}

::xotcl::InfoSlot public method delete {-nocomplain:switch obj prop value} {
  #puts stderr infoslot-delete-[self args]
  $obj $prop [:delete_value $obj $prop [$obj info $prop] $value]
}

############################################
# InterceptorSlot
############################################
::xotcl::MetaSlot alloc ::xotcl::InterceptorSlot

::xotcl::relation ::xotcl::InterceptorSlot superclass ::xotcl::InfoSlot
::xotcl::alias ::xotcl::InterceptorSlot set ::xotcl::relation ;# for backwards compatibility
::xotcl::alias ::xotcl::InterceptorSlot assign ::xotcl::relation

::xotcl::InterceptorSlot public method get {obj prop} {
  ::xotcl::relation $obj $prop
}
::xotcl::InterceptorSlot public method add {obj prop value {pos 0}} {
  if {![set :multivalued]} {
    error "Property $prop of ${:domain}->$obj ist not multivalued"
  }
  set oldSetting [::xotcl::relation $obj $prop]
  # use uplevel to avoid namespace surprises
  uplevel [list ::xotcl::relation $obj $prop [linsert $oldSetting $pos $value]]
}
::xotcl::InterceptorSlot public method delete {-nocomplain:switch obj prop value} {
  uplevel [list ::xotcl::relation $obj $prop [:delete_value $obj $prop [::xotcl::relation $obj $prop] $value]]
}

############################################
# system slots
############################################
proc ::xotcl::register_system_slots {os} {
  ${os}::Object alloc ${os}::Class::slot
  ${os}::Object alloc ${os}::Object::slot
  
  ::xotcl::InfoSlot create ${os}::Class::slot::superclass -type relation
  ::xotcl::alias           ${os}::Class::slot::superclass assign ::xotcl::relation
  ::xotcl::InfoSlot create ${os}::Object::slot::class -type relation
  ::xotcl::alias           ${os}::Object::slot::class assign ::xotcl::relation

  ::xotcl::InterceptorSlot create ${os}::Object::slot::mixin \
      -type relation -methodname object-mixin

  ::xotcl::InterceptorSlot create ${os}::Object::slot::filter \
      -elementtype "" -type relation

  ::xotcl::InterceptorSlot create ${os}::Class::slot::mixin \
      -type relation -methodname class-mixin
  ::xotcl::InterceptorSlot create ${os}::Class::slot::filter \
      -type relation -methodname filter-mixin

  # create tho conveniance slots to allow configuration of 
  # object-slots for classes via object-mixin
  ::xotcl::InterceptorSlot create ${os}::Class::slot::object-mixin \
      -type relation
  ::xotcl::InterceptorSlot create ${os}::Class::slot::object-filter \
      -elementtype "" -type relation

  # We could define a mixin on class, the calls always class-mixin.
  # therfore, 
  #::xotcl::InterceptorSlot create ${os}::Class::slot::mixin \
  #    -type relation -methodname class-mixin
}
::xotcl::register_system_slots ::xotcl2

############################################
# Attribute slots
############################################
::xotcl::MetaSlot __invalidateobjectparameter
::xotcl::MetaSlot create ::xotcl::Attribute -superclass ::xotcl::Slot

createBootstrapAttributeSlots ::xotcl::Attribute {
  {value_check once}
  initcmd
  valuecmd
  valuechangedcmd
  arg
}

::xotcl::Attribute method __default_from_cmd {obj cmd var sub op} {
  #puts "GETVAR [::xotcl::self proc] obj=$obj cmd=$cmd, var=$var, op=$op"
  $obj trace remove variable $var $op [list [::xotcl::self] [::xotcl::self proc] $obj $cmd]
  ::xotcl::setinstvar $obj $var [$obj eval $cmd]
}
::xotcl::Attribute method __value_from_cmd {obj cmd var sub op} {
  #puts "GETVAR [::xotcl::self proc] obj=$obj cmd=$cmd, var=$var, op=$op"
  ::xotcl::setinstvar $obj $var [$obj eval $cmd]
}
::xotcl::Attribute method __value_changed_cmd {obj cmd var sub op} {
  # puts stderr "**************************"
  # puts "valuechanged obj=$obj cmd=$cmd, var=$var, op=$op, ...\n$obj exists $var -> [::xotcl::setinstvar $obj $var]"
  eval $cmd
}
::xotcl::Attribute method check_single_value { {-keep_old_value:boolean true} value predicate type obj var} {
  #puts "+++ checking single value '$value' with $predicate ==> [expr $predicate]"
  if {![expr $predicate]} {
    if {[$obj exists __oldvalue($var)]} {
      ::xotcl::setinstvar $obj $var [::xotcl::setinstvar $obj __oldvalue($var)]
    } else {
      $obj unset -nocomplain $var
    }
    error "'$value' is not of type $type"
  }
  if {$keep_old_value} {::xotcl::setinstvar $obj __oldvalue($var) $value}
  #puts "+++ checking single value done"
}

::xotcl::Attribute method check_multiple_values {values predicate type obj var} {
  foreach value $values {
    :check_single_value -keep_old_value false $value $predicate $type $obj $var
  }
  ::xotcl::setinstvar $obj __oldvalue($var) $value
}
::xotcl::Attribute method mk_type_checker {} {
  puts stderr "[self] [self proc]"
  set __initcmd ""
  if {[:exists type]} {
    if {[::xotcl::is ${:type} class]} {
      set predicate [subst -nocommands {
	[::xotcl::is \$value object] && [::xotcl::is \$value type ${:type}]
      }]
    } elseif {[llength ${:type}]>1} {
      set predicate "\[${:type} \$value\]"
    } else {
      #set predicate "\[string is ${:type} \$value\]"
      set predicate "\[:type=${:type} ${:name} \$value\]"
    }
    #puts stderr predicate=$predicate
    append :valuechangedcmd [subst {
      [expr {${:multivalued} ? ":check_multiple_values" : ":check_single_value"
           }] \[::xotcl::setinstvar \$obj ${:name}\] \
	  {$predicate} [list ${:type}] \$obj ${:name}
    }]
    append __initcmd [subst -nocommands {
      if {[:exists ${:name}]} {set :__oldvalue(${:name}) [set :${:name}]}\n
    }]
  }
  return $__initcmd
}
::xotcl::Attribute method init {} {
  next ;# do first ordinary slot initialization
  # there might be already default values registered on the class
  set __initcmd ""
  if {[:exists default]} {
  } elseif [:exists initcmd] {
    append __initcmd ":trace add variable [list ${:name}] read \
	\[list [::xotcl::self] __default_from_cmd \[::xotcl::self\] [list [set :initcmd]]\]\n"
  } elseif [:exists valuecmd] {
    append __initcmd ":trace add variable [list ${:name}] read \
	\[list [::xotcl::self] __value_from_cmd \[::xotcl::self\] [list [set :valuecmd]]\]"
  }
  set valueParam [::xotcl::parameterFromSlot [self] "value"]
  if {$valueParam ne "value"} {
    if {[set :multivalued]} {
      :method check_single_value [list $valueParam] {return 1}
      :method check_multiple_values list {foreach a $list {:check_single_value $a}}
      #puts stderr "adding multiple assignmethod for [self] with $valueParam"
      :method assign [list obj var value] {
        :check_multiple_values $value
        ::xotcl::setinstvar $obj $var $value
      }
    } else {
      #puts stderr "adding single assignmethod for [self] with $valueParam"
      :method assign [list obj var $valueParam] {::xotcl::setinstvar $obj $var $value}
    }
  }
  #append __initcmd [:mk_type_checker]
  if {[:exists valuechangedcmd]} {
    append __initcmd ":trace add variable [list ${:name}] write \
	\[list [::xotcl::self] __value_changed_cmd \[::xotcl::self\] [list [set :valuechangedcmd]]\]"
  }
  if {$__initcmd ne ""} {
    set :initcmd $__initcmd
  }
}

# mixin class for decativating all value checks in slots
::xotcl2::Class create ::xotcl::Slot::Nocheck {
  :method check_single_value args {;}
  :method check_multiple_values args {;}
  :method mk_type_checker args {return ""}
}
# mixin class for optimizing slots
::xotcl2::Class create ::xotcl::Slot::Optimizer {
  :method method args  {::xotcl::next; :optimize}
  :method forward args {::xotcl::next; :optimize}
  :method init args    {::xotcl::next; :optimize}
  :public method optimize {} {
    #puts stderr OPTIMIZER
    if {[set :multivalued]} return
    if {[set :defaultmethods] ne {get assign}} return
    #puts stderr assign=[:info callable -which assign]
    if {[:info callable -which assign] ne "::xotcl::Slot alias assign ::xotcl::setinstvar"} return
    if {[:info callable -which get]    ne "::xotcl::Slot alias get ::xotcl::setinstvar"} return
    #puts stderr "**** optimizing       [${:domain} info method definition ${:name}]"
    ::xotcl::setter ${:domain} {*}[expr {${:per-object} ? "-per-object" : ""}] ${:name}
  }
}
# register the optimizer per default
::xotcl::Attribute mixin add ::xotcl::Slot::Optimizer

##################################################################
# Create a mixin class to overload method "new", such it does not allocate
# new objects in ::xotcl::*, but in the specified object (without
# syntactic overhead).
#
::xotcl2::Class create ::xotcl::ScopedNew -superclass ::xotcl2::Class
createBootstrapAttributeSlots ::xotcl::ScopedNew {
  {withclass ::xotcl2::Object}
  inobject
}
::xotcl::ScopedNew method init {} {
  :public method new {-childof args} {
    ::xotcl::importvar [::xotcl::self class] {inobject object} withclass
    if {![::xotcl::is $object object]} {
      $withclass create $object
    }
    eval ::xotcl::next -childof $object $args
  }
}

#
# change the namespace to the specified object and create
# objects there. This is a friendly notation for creating
# nested object structures. Optionally, creating new objects
# in the specified scope can be turned off.
#
::xotcl2::Object public method contains {
   {-withnew:boolean true}
   -object
   {-class ::xotcl2::Object}
   cmds
 } {
  if {![info exists object]} {set object [::xotcl::self]}
  if {![::xotcl::is $object object]} {$class create $object}
  $object requireNamespace
  if {$withnew} {
    set m [::xotcl::ScopedNew new \
	       -inobject $object -withclass $class -volatile]
    ::xotcl2::Class mixin add $m end
    namespace eval $object $cmds
    ::xotcl2::Class mixin delete $m
  } else {
    namespace eval $object $cmds
  }
}
::xotcl2::Class forward slots %self contains \
    -object {%::xotcl::dispatch [::xotcl::self] -objscope ::subst [::xotcl::self]::slot}

############################################
# Define method "parameter" for backward 
# compatibility and convenience
############################################
::xotcl2::Class public method parameter arglist {
  if {![::xotcl::is [::xotcl::self]::slot object]} {
    ::xotcl2::Object create [::xotcl::self]::slot
  }

  foreach arg $arglist {
    set l [llength $arg]
    set name [lindex $arg 0]
    set colonPos [string first : $name]
    if {$colonPos > -1} {
      set properties [string range $name [expr {$colonPos+1}] end]
      set name [string range $name 0 [expr {$colonPos -1}]]
      foreach property [split $properties ,] {
	if {$property eq "required"} {
	  set required 1
	} elseif {[string match arg=* $property]} {
	  set argument [string range $property 4 end]
	} else {
	  set type $property
	}
      }
    }
    set cmd [list ::xotcl::Attribute create [::xotcl::self]::slot::$name]
    if {[info exists type]} {
      lappend cmd -type $type
      unset type
    }
    if {[info exists argument]} {
      lappend cmd -arg $argument
      unset argument
    }
    if {[info exists required]} {
      lappend cmd -required 1
      unset required
    }

    if {$l == 1} {
      eval $cmd
      #puts stderr "parameter $arg without default -> $cmd"
    } elseif {$l == 2} {
      lappend cmd -default [lindex $arg 1]
      eval $cmd
    } elseif {$l == 3 && [lindex $arg 1] eq "-default"} {
      lappend cmd -default [lindex $arg 2]
      eval $cmd
    } else {
      set paramstring [string range $arg [expr {[string length $name]+1}] end]
      if {[string match {[$\[]*} $paramstring]} {
	lappend cmd -default $paramstring
	eval $cmd
	continue
      }

      set po ::xotcl2::Class::Parameter
      puts stderr "deprecated parameter usage '$arg'; use '-slots {Attribute ...}' instead"

      set cl [::xotcl::self]
      ::xotcl::setinstvar $po name $name
      ::xotcl::setinstvar $po cl [::xotcl::self]
      ::eval $po configure [lrange $arg 1 end]

      if {[$po exists extra] || [$po exists setter] ||
	  [$po exists getter] || [$po exists access]} {
	::xotcl::importvar $po extra setter getter access defaultParam
	if {![info exists extra]} {set extra ""}
	if {![info exists defaultParam]} {set defaultParam ""}
	if {![info exists setter]} {set setter set}
	if {![info exists getter]} {set getter set}
	if {![info exists access]} {set access ::xotcl::my}
	$cl public method $name args "
         if {\[llength \$args] == 0} {
           return \[$access $getter $extra $name\]
         } else {
           return \[eval $access $setter $extra $name \$args $defaultParam \]
         }"
	foreach instvar {extra defaultParam setter getter access} {
	  $po unset -nocomplain $instvar
	}
      } else {
	.setter $name
      }
    }
  }
  ::xotcl::setinstvar [::xotcl::self]::slot __parameter $arglist
}

##################################################################
# new the slots are defined; now we can defines the Objects or 
# classes with parameters more easily.
##################################################################

#
# copy/move implementation
#
::xotcl2::Class create ::xotcl::CopyHandler -parameter {
  {targetList ""}
  {dest ""}
  objLength
} {

  :method makeTargetList {t} {
    lappend :targetList $t
    # if it is an object without namespace, it is a leaf
    if {[::xotcl::is $t object]} {
      if {[$t info hasnamespace]} {
        # make target list from all children
        set children [$t info children]
      } else {
        # ok, no namespace -> no more children
        return
      }
    }
    # now append all namespaces that are in the obj, but that
    # are not objects
    foreach c [namespace children $t] {
      if {![::xotcl::is $c object]} {
        lappend children [namespace children $t]
      }
    }
    
    # a namespace or an obj with namespace may have children
    # itself
    foreach c $children {
      :makeTargetList $c
    }
  }


  :method copyNSVarsAndCmds {orig dest} {
    ::xotcl::namespace_copyvars $orig $dest
    ::xotcl::namespace_copycmds $orig $dest
  }

  # construct destination obj name from old qualified ns name
  :method getDest origin {
    set tail [string range $origin [set :objLength] end]
    return ::[string trimleft [set :dest]$tail :]
  }
  
  :method copyTargets {} {
    #puts stderr "COPY will copy targetList = [set :targetList]"
    foreach origin [set :targetList] {
      set dest [:getDest $origin]
      if {[::xotcl::is $origin object]} {
        # copy class information
        if {[::xotcl::is $origin class]} {
          set cl [[$origin info class] create $dest -noinit]
          # class object
          set obj $cl
          $cl superclass [$origin info superclass]
          ::xotcl::assertion $cl class-invar [::xotcl::assertion $origin class-invar]
          ::xotcl::relation $cl class-filter [::xotcl::relation $origin class-filter]
          ::xotcl::relation $cl class-mixin [::xotcl::relation $origin class-mixin]
          :copyNSVarsAndCmds ::xotcl::classes$origin ::xotcl::classes$dest
        } else {
          # create obj
          set obj [[$origin info class] create $dest -noinit]
        }
        # copy object -> may be a class obj
        ::xotcl::assertion $obj check [::xotcl::assertion $origin check]
        ::xotcl::assertion $obj object-invar [::xotcl::assertion $origin object-invar]
        ::xotcl::relation $obj object-filter [::xotcl::relation $origin object-filter]
        ::xotcl::relation $obj object-mixin [::xotcl::relation $origin object-mixin]
        if {[$origin info hasnamespace]} {
          $obj requireNamespace
        }
      } else {
        namespace eval $dest {}
      }
      :copyNSVarsAndCmds $origin $dest
      foreach i [$origin info forward] {
        eval [concat $dest forward $i [$origin info forward -definition $i]]
      }
      if {[::xotcl::is $origin class]} {
        foreach i [$origin info instforward] {
          eval [concat $dest instforward $i [$origin info instforward -definition $i]]
        }
      }
      set traces [list]
      foreach var [$origin info vars] {
        set cmds [::xotcl::dispatch $origin -objscope ::trace info variable $var]
        if {$cmds ne ""} {
          foreach cmd $cmds {
            foreach {op def} $cmd break
            #$origin trace remove variable $var $op $def
            if {[lindex $def 0] eq $origin} {
              set def [concat $dest [lrange $def 1 end]]
            }
            $dest trace add variable $var $op $def
          }
        }
      }
      #puts stderr "====="
    }
    # alter 'domain' and 'manager' in slot objects for classes
    foreach origin [set :targetList] {
      if {[::xotcl::is $origin class]} {
        set dest [:getDest $origin]
        foreach oldslot [$origin info slots] {
          set newslot ${dest}::slot::[namespace tail $oldslot]
          if {[$oldslot domain] eq $origin}   {$newslot domain $cl}
          if {[$oldslot manager] eq $oldslot} {$newslot manager $newslot}
        }
      }
    }
  }
  
  :public method copy {obj dest} {
    #puts stderr "[::xotcl::self] copy <$obj> <$dest>"
    set :objLength [string length $obj]
    set :dest $dest
    :makeTargetList $obj
    :copyTargets
  }
}


::xotcl2::Object public method copy newName {
  if {[string compare [string trimleft $newName :] [string trimleft [::xotcl::self] :]]} {
    [::xotcl::CopyHandler new -volatile] copy [::xotcl::self] $newName
  }
}

::xotcl2::Object public method move newName {
  if {[string trimleft $newName :] ne [string trimleft [::xotcl::self] :]} {
    if {$newName ne ""} {
      :copy $newName
    }
    ### let all subclasses get the copied class as superclass
    if {[::xotcl::is [::xotcl::self] class] && $newName ne ""} {
      foreach subclass [:info subclass] {
        set scl [$subclass info superclass]
        if {[set index [lsearch -exact $scl [::xotcl::self]]] != -1} {
          set scl [lreplace $scl $index $index $newName]
          $subclass superclass $scl
        }
      }	
    }
    :destroy
  }
}

#######################################################
# some utilities
#######################################################

# documentation stub object -> just ignore per default.
# if xoDoc is loaded, documentation will be activated
::xotcl2::Object create ::xotcl::@ {
  :method unknown args {}
}





#######################################################################


# common code for all xotcl versions
namespace eval ::xotcl {

  # export the contents for all xotcl versions
  namespace export @ Attribute

  # if HOME is not set, and ~ is resolved, Tcl chokes on that
  if {![info exists ::env(HOME)]} {set ::env(HOME) /root}
  set ::xotcl::confdir ~/.xotcl
  set ::xotcl::logdir $::xotcl::confdir/log
  
  # return platform aware temp directory
  proc tmpdir {} {
    foreach e [list TMPDIR TEMP TMP] {
      if {[info exists ::env($e)] \
              && [file isdirectory $::env($e)] \
              && [file writable $::env($e)]} {
        return $::env($e)
      }
    }
    if {$::tcl_platform(platform) eq "windows"} {
      foreach d [list "C:\\TEMP" "C:\\TMP" "\\TEMP" "\\TMP"] {
        if {[file isdirectory $d] && [file writable $d]} {
          return $d
        }
      }
    }
    return /tmp
  }

  proc use {version} {
    set callingNs [uplevel {namespace current}]
    switch -exact $version {
      xotcl1 {
	package require xotcl1
	puts stderr "current=[namespace current], ul=[uplevel {namespace current}]"
	if {$callingNs ne "::xotcl"} {uplevel {namespace import -force ::xotcl::*}}
      }
      default {
	if {$callingNs ne "::xotcl"} {uplevel {namespace import -force ::xotcl::*}}
	if {$callingNs ne "::xotcl2"} {uplevel {namespace import -force ::xotcl2::*}}
      }
    }
  }

  unset bootstrap
}