[Twisted-Python] Twisted & Qt

glyph at divmod.com glyph at divmod.com
Mon Sep 25 17:39:44 EDT 2006

On Mon, 25 Sep 2006 08:01:46 -0700, Ed Suominen <general at eepatents.com> wrote:

>As an example and a contribution, I offer the following (GPL'd) module:
>http://deadbeefbabe.org/paste/1996 (syntax-highlighted version),
>http://foss.eepatents.com/misc/qt-twisted-dialog.py (source). It allows
>you to construct a non-blocking modal dialog, immediately obtaining a
>deferred to the user's eventual input.

Thanks very much for that pointer.  I knew this was possible but it is the first working example I've seen of it!

>As an aside, I would be interested in people's viewpoints about whether
>the Qt reactor is suitable for Twisted's MIT-style license, given that
>it doesn't actually import any Qt code itself. It leaves that step up to
>the user with the installation of a reactor into the Qt application
>object. As every Qt user probably knows, the Qt library itself is
>dual-licensed under either the GPL or Trolltech's proprietary license.

It does "import" qt in the sense that there is an import line at the top of the file which will load the library.  IANAL, but as far as I know it is a matter of debate whether this sort of reference constitutes a "derivative work" under copyright law.  As such, it would be best to get Riverbank and Trolltech on the record as to their respective opinions on whether licensing such code as MIT is a GPL violation, since I believe PyQt is clearly a derivative work of Qt itself, and therefore both companies are potential enforcers of the license in this case.  Is anyone aware of the correct point of contact for these inquiries?

If they do indeed consider it a violation, we'd have to remove it from Twisted.  However, in that case, I would be happy to contribute the qt reactor to Riverbank and have them distribute it (under the GPL) with PyQt rather than us distributing it together with Twisted.  This might be a good excuse to finally make reactors properly pluggable.

As for this thread, I'd appreciate it if only people with relevant legal expertise and/or information from a responsible party at Trolltech or Riverbank would reply.  I know license debates are always fun to get involved in, but this is not the appropriate forum.  Twisted's MIT license is a matter of policy and is not open to debate.

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