GPL, BSD, commercial

Michele Bosi michele.bosi at
Thu Apr 2 07:40:43 UTC 2009

Yes, I agree with you Matt, the problem is the non-trivial definition
of derivative-work. In fact some people believe that the simple fact
of subclassing in your C++ sources a class that is released under the
LGPL makes your sources a derivative-work. In my opinion this is not
the case as the LGPL point 5 is very general and does not make or
imply any exception based on the kind of language one uses or based on
what's written in the "work that uses the Library". Of course it would
be different if my sources contained parts of the library.
Furthermore, I would say that a line of code "MyClass: public
ParentClass" where ParentClass is defined in the LGPL library, should
not constitute a derivative work, because "ParentClass" should not be
considered "including a portion of the Library". In fact if the simple
act of using in my sources an identifier declared or implemented in
the LGPL library constituted a derivative work than it seems to me
that there would be *no way* to apply section 5 of the LGPL ever and
for noone. In order for section 5 to have sense and to be usable at
all, it must imply that one can freely use identifiers "coming" from
an LGPL licensed sources. If this wasn't the intention of the LGPL,
than probably they could have just dropped section 5 altogether since
it cannot be exploited by anyone. Or at least this is my personal
interpretation of the subject.


On Thu, Apr 2, 2009 at 6:00 AM, Matthew Flaschen
<matthew.flaschen at> wrote:
> Wilson, Andrew wrote:
>> Matt, if "my program" in this context is an original work where Michele is
>> the copyright owner and which is not derived from GPL code, then
>> I think his question may be about dual licensing of his original code,
>> not the (L)GPL libraries. In that case, the answer for dual licensing
>> GPL/proprietary of Michele's original code would be "probably yes."
> Any code that is owned solely by Michele and not a derivative of any
> other code can be dual-licensed without constraints.  Is that what
> you're saying?  If so, I agree.  Of course, determining what is a
> derivative work is non-trivial.
>> I am not a lawyer.  Michele, you need a real lawyer for
>> these questions.
> Agreed.  As already said, this is not legal advice.  You can only get
> that from a lawyer.
> Matt Flaschen

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