Andrew,

thank you for your explanations. I have a few more - concrete -
questions:

"Andrew C. Greenberg" wrote:
> 
> >How far can someone 'copy' an existing implementation of a commercial
> >Smalltalk?
> >- Totally?
> >- Just rename some vars?
> >- Change the class structure?
> >- Change some algorithms?
> 
> The following provides broad summaries of U.S. law only.  Your
> mileage may vary.
> 
> Copyright protects expressions of ideas, and not ideas itself.  To
> the extent a program implements a particular functionality, that
> functionality may be recreated without reference to the expression.
> If the expression is only one of a few limited ways in which the
> functionality may be implemented, it probably isn't protected by
> copyright at all (the so-called "merger doctrine" where the idea
> merges with the expression).
> 
> Still further, you can only infringe if you are guilty of copying or
> deriving from the original work.  If you are presented with a
> detailed specification, even if derived from an existing work, that
> embodies only the ideas of the work, and develop a program from the
> specification without reference to the original (a so-called
> "clean-room" implementation), there is no infringement.  (Practice
> this only witht the guidance of competent counsel

If there is any...

> -- "clean rooming"
> is difficult to do right, and a disaster if done wrong).

Does this mean that it is possible to e.g.
- take the class hierarchy of VW Filename,
- take all method names of methods called from outside the class
hierarchy (the interface),
- program the same functionality?

In short: Implement the same functionality with the same interface?

What about using the 'private' methods?


Stephan

> 
> So, while there is great latitude to borrow concepts and ideas from
> an existing functional work, any of the preceding acts from the
> original post -- total copying or changes with just a few minor
> mechanical variations, or even derivations with sophisticated
> variations -- may well be infringement.  In short, the devil is in
> the details.  Don't count, however, on appropriating expression from
> a work, with or without changes, and then incorporating portions of
> it directly in your own.  You are free to borrow the IDEAS, not the
> expressions.
> --
> Andrew C. Greenberg             acg at netwolves.com
> V.P. Eng., R&D,                 813.885.2779 (office)
> Netwolves Corporation           813.885.2380 (facsimile)
> www.netwolves.com

-- 
Stephan Rudlof (sr at evolgo.de)
   "Genius doesn't work on an assembly line basis.
    You can't simply say, 'Today I will be brilliant.'"
    -- Kirk, "The Ultimate Computer", stardate 4731.3