[dkf] has been doing [OO], too - here [http://www.man.ac.uk/~zzcgudf/tcl/oo2.tcl] is his pure-Tcl approach with the following features:
   * requires Tcl 8.5a2 or later ([dict] and many other features too)
   * about 16KB of size
   * prototype-based, but which has a class-based face built on top
   * in an earlier phase, presented at the 2004 Tcl convention (Powerpoint: [http://www.man.ac.uk/~zzcgudf/tcl/tcl2k4_presentation.pps] PDF: [http://www.man.ac.uk/~zzcgudf/tcl/tcl2k4_paper.pdf])

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Here's the next version, '''oo3.tcl'''[http://www.man.ac.uk/~zzcgudf/tcl/oo3.tcl]

Current methods of the ''Object'' class/object:
   !:   Return the object's persistent state handle
   ? ''<handle>'':   Convert a persistent state handle to a callable object
   addRef:   Increment the object's reference count
   as ''<variable>'':   Bind object lifetime to the lifetime of a (presumably local) variable
   clone:   Produce a copy of the object, returning the name of the new object
   constructor:   Magic method called from '''new''' command
   delRef:   Decrement the object's reference count and delete if reaches zero
   delegate ''<method>'' to ''<object>'':   Arrange for a method (or all unknown methods if ''method'' is *) to be executed by another object (or object-like entity like a Tk widget)
   delete:   Delete the object, calling any destructor defined
   derive ''<class>'' ''?namespace?'' ''<definition>'':   Create a new object through subclassing
   destructor:   Callback for when the object is '''delete'''d
   eq ''<object>'':   Is the argument object equal to this object?
   get ''<field>'' ''?key?'':   Read an object field
   get parent:   Return the parent/superclass object, or empty string if no parent exists
   isa ''<object>'':   Test if the object is derived from another one
   linkArray ''?field?'' ''<variable>'':   Return the name of an array that is linked to the given dictionary-containing field
   linkVar ''?field?'' ''<variable>'':   Return the name of a variable that is linked to the given field
   methods ''?name?'' ''?arguments body?'':   Introspect and create object methods
   property ''<name>'' ''<value>'':   Label the field as a property (bound to local variables when executing this object's methods) for all methods declared after this method is called.
   return:   Undo the linking set up with '''as''' and return the object
   set ''<field>'' ''?key?'' ''<value>'':   Write an object field
   unset ''<field>'' ''?key?'':   Destroy an object field
Public helper procedures:
   super ''<method>'' ''?args?'':   Call method using superclass's definition
   new ''<class>'' ''?args?'':   Create a new object (based on the given "class" object) and call its constructor with args
The code has a self-test mode too, of course. This currently does some timing tests, and demonstrates the capabilities of the code in relation to error handling, variable linking and delegation.

Provided subclass-like objects are ''Collection'', ''List'', ''UniqueList'', and ''Map'' which together form a basic aggregate type framework.

''Design Notes''

   * The '''property''' method acts like the '''set''' method except that it also adds the field to the list of fields to be bound to local variables during the body of methods. The '''methods''' method uses the current value of this list (which, like almost everything, is inheritable) whenever it creates a method. This means that methods only ever see directly those variables that have been declared with '''property''' when they were created; they can only inspect and update variables in subclasses using the '''get''' and '''set''' methods.
   * The '''derive''' method is for creating new classes from existing ones, but any object can act as a class because this is a prototype-based OO scheme.  It is the '''new''' procedure that really calls the constructor, and the '''delete''' method that really calls the destructor.
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[lv] is some background, alternative to the paper, or the paper or powerpoint or something available?

[DKF]: Not yet. :^)

Look at [Conference Slides] for pointers.

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''[escargo] 11 Dec 2004'' - I would find it interesting to see a summary of changes between versions 1, 2, and 3.

[DKF]:  Hmm.  These are the main things that I can think of right now... :^)

'''v1 ��� 2'''

Reimplemented virtually from the ground up; switch to using prototypes instead of jury-rigged classes.

'''v2 ��� 3'''

Introduction of the property exposure rule (outlined above) that greatly simplified things internally.
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[Category Object Orientation]