[Zarutian] 18. november 2005:

TeaTime is the underlying object system of Croquet. (Or that is as much as I gather)

see http://www.opencroquet.org/Croquet_Technologies/architecture.html for more details.

And the code below was inspired by the TeaTime concept:

 # below code by Zarutian is hereby in the public domain
 proc thingy {name} { proc $name args "namespace eval $name \$args" }
 proc trackedThingy {name} {
   proc $name args [string map [list @name $name] {
     namespace eval @name lappend __history [list $args]
     namespace eval @name set this @name
     namespace eval @name $args
   }]
   $name proc undo {} {
     # there is a potential proplem with this proc
     # it doesnt notify subcomponents of the undo
     # possible solution would be adding an element
     # to each element of __history that stated what
     # other objects were affected
     variable __history
     variable this
     set local_this $this
     set local_history $__history
     if {[llength $__history] > 2} {
       namespace delete [namespace current]
       if {[lindex $local_history end] == "undo"} {
         set local_history [lrange $local_history 0 end-1]
       }
       foreach invocation [lrange $local_history 0 end-1] {
         eval [concat $local_this $invocation]
       }
     } else {
       # err here or not?
     }
   }
 }
 proc replicatedThingy {name connector} {
   proc $name args [string map [list @name $name @connector [list $connector]] {
     if {![was-called-by? @connector]} {
       # to prevent invocation feedback (similiar to acaustic feedback)
       @connector invoke @name $args
     }
     namespace eval @name $args
   }]
 }
 proc was-called-by? {commandName} {
   set callstack [list]
   for {set i [info level]} {$i >= 0} {incr i -1} {
     lappend callstack [info level $i]
   }
   foreach call $callstack {
     if {[lindex $call 0] == $commandName} { return yes }
   }
   return no
 }

Some of the above code might be more at home elsewhere.