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Re: More GPL questions

From: Stefaan A Eeckels
Subject: Re: More GPL questions
Date: Wed, 18 Oct 2006 00:57:02 +0200

On Tue, 17 Oct 2006 23:49:05 +0200
David Kastrup <> wrote:

> John Hasler <> writes:
> > Stefaan A Eeckels writes:
> >
> >> I firmly believe that the OP can distribute his example programs,
> >> or even complete, useful programs in source format, under whatever
> >> license he fancies, without any recourse for the copyright holders
> >> of the libraries and OSes that might - if the licensee so desires -
> >> be used to run the programs.
> >
> > I agree with you.  A program that, when compiled, could be linked
> > with Qt to form a useful program does not necessarily include any
> > protected elements of Qt.
> But it may be based on such elements.

It references functions, classes or methods implemented in the library.

The names of these functions, classes or methods are not subject to
copyright, or else none of the GNU re-implementations of existing
libraries would be possible, even using clean-room approaches. 

In addition, re-implementations are without the shadow of a doubt "based
on" the existing library even if they contain no protected elements. It
all depends on the definition of "based on", which here would be
"taking its inspiration and API from the existing library".

You define "based on" for source code as "not runnable in compiled
format without the library and containing references to the library's
API". The way I would define "based on" for source code is
"incorporating modified or unmodified source code from the library".

Your definitions opens, IMHO, more cans of worms you'd ever wanted to
open in an entire lifetime.

> Anyway, for Qt the point is quite moot, since an API-compatible
> library (Qt commercial) under a different license is available, and
> so source code written for Qt does not require a GPLed library
> version to run.  The code might be useless without Qt, but not so
> without _GPLed_ Qt.

I believe neither the existence of another library or another license,
nor the "usefulness" of source code without the called libraries or
the supporting OS has anything to do with its copyright status. 

Usefulness is not a criterion for software to be a derivative work or
not. An OS (even compiled) is useless without a computer with the
appropriate instruction set, but that doesn't make it a derivative
work of the processor's microcode, design, or assembly language
mnemonics (I still have Intel's 8080 Assembly Language manual, which
mentions at the bottom of every page of the first chapter that the
mnemonics are copyrighted: "ALL MNEMONICS © 1974, 1975, 1976, 1977 INTEL

Stefaan A Eeckels
"The most common of all follies is to believe passionately in 
the palpably not true. It is the chief occupation of mankind." 
    --H. L. Mencken 

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