Re: Gtkmm, LGPL and C++

[Neil <mail neilramsden co uk>]

Thanks, Chris.

Chris Vine wrote:
> Having read the LGPL, I personally would not 
> release important proprietary code based on a templated library licenced 
> under it, such as libsigc++ (which is where the problem, if there is one, 
> mainly resides with gtkmm), but I imagine that there are those who take a 
> different view, such as Jonathon.

There are certainly mixed messages. Forgetting about my own position for 
the moment (though obviously I will need to resolve it), searching on 
'closed' came up with this thread:

http://www.mail-archive.com/gtkmm-list gnome org/msg03094.html

This has a lot of good stuff in it that we're re-treading here, not 
least your own. It ends with Murray reluctantly agreeing to contact with 
FSF people directly on how to handle templates et al.

I imagine the lure of licence clarification is likely to create major 
yawning rather than yearning and it's not obvious that there's been any 
resolution of this.

Given that this is a repeated issue, could we at least get something 
tangible this time round for other potential library users? Perhaps eg. 
a FAQ addressing the position of Gtkmm and LGPL as we understand it?

The key points might be:

- intent is allowing use through shared libraries in all projects both 
open and proprietary;

- but there are q's about whether the LGPL strictly allows this 
especially regarding longer templates (>10 lines);

- the gtkmm team is (or perhaps isn't) considering the possibility of 
special additional provisions to the LGPL to allow for templates of any 
length;

- the team would(???) require any wording to:

 a) allow the gtkmm code to be used in another application, open source 
or proprietary if changes are made, and
 b) share changes back out so all can benefit

- inheritance isn't an issue under LGPL, because of XXX.

In the spirit of (L)GPL, I would guess that the team would(???) also 
require any wording to do the following.

Suppose I create a closed source application called Cerrado using gtkmm 
and sell to Kate who has an enhanced variant of gtkmm (perhaps her own 
mods). Then you'd probably want Kate to have a fighting chance (limited 
by eg. any modified templates) of running Cerrado against her version of 
gtkmm and the right to distribute her gtkmm version for other Cerrado 
users to use. Hence the shared library solution. (If you do require 
this, I think it would rule out the libstdc++ licence.)

Jonathon asked if I was willing to work with you all on clearing up the 
ambiguity. If we can get somewhere useful, then I would be.

Ultimately, any end-point would probably only be meaningful if it agreed 
with libsigc++ team.

Neil.