[vtk-developers] Scope of VTK and it's potential as a common research language

[David Cole]

On Sun, Jan 31, 2010 at 2:31 PM, Berk Geveci <berk.geveci at kitware.com>wrote:

> I don't agree. Here are two sections:
>
> 0. Additional Definitions.
>
> ...
>
> A “Combined Work” is a work produced by combining or linking an
> Application with the Library. The particular version of the Library
> with which the Combined Work was made is also called the “Linked
> Version”.
>
> ...
>
> 4. Combined Works.
>
> You may convey a Combined Work under terms of your choice that, taken
> together, effectively do not restrict modification of the portions of
> the Library contained in the Combined Work and reverse engineering for
> debugging such modifications, if you also do each of the following:
>
> ...
>
>
> I read these together to conclude that a binary that is compiled from
> any code that includes Eigen is "Combined Work" (a work produced by
> combining through the inclusion of templates). If that is the case, 4
> would apply and hence the reverse engineering clause. It would be
> against the spirit of LGPL to grant templated libraries less
> protection than compiled libraries so why would they leave such a
> loophole?
>
> Of course, the copyright holders of Eigen are free to write an
> addendum to the license that explicitly states (4) does not apply.
>
> My vote is to keep Eigen out of core VTK. I wouldn't have any problem
> with releasing an application that brings together VTK and Eigen (and
> Qt for that matter) because I don't see any issues with LGPL's
> requirements but I don't think many of VTK's users that develop
> proprietary apps would share my opinion. We have worked very hard to
> keep VTK's license free of complications and the value Eigen adds is
> not worth wasting all of that effort.
>
> -berk
>
>
I agree with Berk here... Keep Eigen out of core VTK.

Benoit, you keep comparing it to Qt, but Qt is not included by default when
you build VTK. You have to turn it on explicitly to pull it in. That's the
difference here.

It would be most useful if Eigen were built in and on by default (or always
on), but since it has an LGPL license (of whatever flavor), it should be OFF
by default if included in VTK... but if it's OFF, not so useful.


David C.
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