Re: Gtkmm, LGPL and C++

["Jonathon Jongsma" <jonathon jongsma gmail com>]

On 2/9/07, Neil <mail neilramsden co uk> wrote:
> Hi
>
> Gtkmm is really well put together and an inspiring advert for what a
> community can achieve.
>
> I've used it internally and now want to use it for an external
> educational product that I'd need to be able to sell on a commercial basis.
>
> Is there any practical way I can do that without releasing all my code?
> (I don't believe there is.)
>
> Your use of the LGPL for a C++ library that contains template and inline
> code doesn't seem to allow that in practice. (And libsigc++ probably
> goes further in this respect.)
>
> Although you say "Our intent in licensing it in this way is to provide
> it for use through shared libraries in all projects both open and
> proprietary", my reading of the LGPL is that my users would have to have
> the freedom to replace the gtkmm code by a modified version.
>
> The freedom to replace a shared run-time library wouldn't be enough to
> be able modify application code that contains template instantiations.
> At the least, therefore, the LGPL seems to imply that any source code
> that instantiates templates or inline code from gtkmm, needs to be made
> available for re-compiling and linking.
>
> I wonder firstly whether my analysis is correct; and if so, whether that
> is really what you intended in your choice of licence?
>
> Obviously, there's potentially a wider question here over the
> appropriateness of LGPL for any C++ library.
>
> Interestingly, I notice that GNU libstdc++ uses GPL with a runtime
> exception for this reason.
>
> I'd be grateful if you could cast some light on this - I think gtkmm
> deserves to be used as widely as possible and I'd certainly like to know
> whether I can use it legitimately in this particular case.
>
> Many thanks,
> Neil.

This is a question that pops up on the list every couple weeks or
months.  The last time somebody asked, murray said[1]:
"There is no question that gtkmm may be used by closed-source
proprietary applications."

I believe there was some talk in the past about adding explicit
language to the license regarding templates, but nobody has cared
enough to propose language so far.  If you feel you need additional
language in the license, maybe you could propose something?  I think
the intention of the developers is clear, but if you don't feel
comfortable with that, and you're willing to work with us, we might be
able to clear up the ambiguity.

Of course, Murray's opinion would be the one to really pay attention
to, since he's done most of the work and I'm just a minor contributor.

[1] http://www.mail-archive.com/gtkmm-list gnome org/msg07058.html
--
jonner