2012/1/5 Marko Knöbl <m...@knoebls.com> > Hi! I'm new to pythonOCC. So far learning and working with pythonOCC has > been > a really great experience, so I want to say thank you to everyone who has > contributed to this project! >
Hi Marko, Thank you for your support! A short reply to your questions, I'm not really a fan of discussing legal and licensing stuff ;-( > > I have started using pythonOCC and PyQt for writing a free CAD application. > However after some investigations I now think that an application linking > with > both OCC and PyQt would violate the GPL and the application would be > undistributable. Thus I also think that pythonOCC itself is not legally > distributable in its current form as it links with PyQt too. > That's something I identified as an issue since the beginning of the project. > > The Problem > ----------- > First off I want to say that I'm not an expert on free software licensing > and I > could be wrong on this. So I'd like to get some feedback by others on > whether > my assumptions are correct. > > I found out about the problem through a Debian bug report[1] which is > about a > similar problem in the FreeCAD application. FreeCAD has been removed from > Debian testing because of this issue and will not be included in Debian 7 > anymore. According to the bug report the problem about FreeCAD is that it > links with both a library which is licensed under the GPL and with OCC, > which > is licensed under a GPL-incompatible license. > > I think that the same is true about pythonOCC: pythonOCC links with both > PyQt > (GPL) and with OCC (GPL-incompatible). So I think that the distribution of > pythonOCC is violating the GPL. The GPL would require all software which > links > with PyQt to be relicensed under the terms of the GPL as well. This is > possible for software licensed under the LGPL (like pythonOCC), but not for > OCC, which is licensed under the OCTPL. > > Further legal information on combining GPL-software with other software > can be > found in the GNU GPL FAQ[2], in the section "Combining work with code > released > under the GNU licenses". The question on GPL-incompatible libraries[3] > explains that using a GPL-incompatible library with GPL software is not > allowed unless explicitly permitted by the author of the GPL-licensed > software. > > [1] http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=617613 > [2] http://www.gnu.org/licenses/gpl-faq.html > [3] http://www.gnu.org/licenses/gpl-faq.html#GPLIncompatibleLibs > > Possible Solutions > ------------------ > Even though this issue has yet to be confirmed by others I'm already > listing > possible solutions here. These could be considered in order to resolve the > issue if it is confirmed: > 1) Have OCC relicensed under the LGPL: The author of the Debian bug report > talks about a possibility of having OCC relicensed under the LGPL if there > are > enough people trying to persuade Open CASCADE S.A.S. > The best solution IMO, unfortunately it does not depend on me nor any pythonocc contributor. > 2) Get a linking exception in PyQt: PyQt already has 26 linking exceptions > for > many popular free software licenses, so asking its developer to add another > one for the OCTPL might be successful. > I do think that keeping PyQt as a pythonocc dependency is not an requirement anymore since PySide has made much progresses these last months. > 3) Port pythonOCC to PySide: PySide is basically "PyQt under LGPL". Porting > pythonOCC to PySide should be quite easy. > Of course it's the best and easier solution. pythonocc actually uses a ridiculous number of Qt features (only creating a window, a simple menu, catching events). I've been monitoring the PySide project since it was started, but I did not have time to go deeper. Also, I'm working on an OSX machine, which is quite a nightmare to develop pythonocc gui features since the OCC backend relies on X11. Happy Linux users! > > If action has to be taken in order to achieve license-compatibility I'd be > happy to help by writing either mails or code. > I'd be happy too! > > Regards, > Marko > Thank you for the clean structure of your post. Best Regards, Thomas
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