On 22 July 2016 at 20:25, Jean-Michaël Celerier <jeanmichael.celer...@gmail.com> wrote: >> I was pointed out that there's a potential LGPLv3 license > infringement, although I understand where the FUD is coming from, I > think that it is OK to read LGPLv3 source code to get inspired as long > as you don't blindly copy/paste code (In my case i checked out quite a > few articles and forum threads before choosing the Qt way as the best > way to do it for my application). > > There is no infrigement, you can even use directly qFuzzyCompare in your > proprietary code : > From the LGPLv3.0 > > The object code form of an Application may incorporate material from a > header file that is part of the Library. You may convey such object code > under terms of your choice, provided that, if the incorporated material is > not limited to numerical parameters, data structure layouts and accessors, > or small macros, inline functions and templates (ten or fewer lines in > length), you do both of the following: > > a) Give prominent notice with each copy of the object code that the Library > is used in it and that the Library and its use are covered by this License. > b) Accompany the object code with a copy of the GNU GPL and this license > document.
Interesting excerpt indeed. So you can use small inlines and templates of a LGPLv3 header file "under terms of your choice"! What a surprise! This is quite liberal for a so-called "viral" license. I'm using "viral" here because this is quite often the term used to spread FUD, I have personally always liked GNU licenses and have great respect toward all the people behind them. Thanks a lot for pointing that out. Chris > > qFuzzyCompare clearly is in the "inline function ten or fewer lines in > length" case so you can use it without problems and without even requiring > to "give prominent notice". > > Best > > Jean-Michaël > > > On Fri, Jul 22, 2016 at 10:10 AM, Benjamin TERRIER <b.terr...@gmail.com> > wrote: >> >> Hi, >> >> My personal experience is that it will depend on the countries in >> which you develop >> and distribute your software. >> >> In France for instance software are protected by "author's rights" which >> implies >> that to be protected a piece of code must have some kind of creativity >> and/or >> originality. So my guess would be that according to French laws >> qFuzzyCompare >> cannot be protected and thus can be copy-pasted without infringing >> neither the law >> nor the LGPL. >> Note that this is only a guess as only judges can rule if a piece of >> code is original >> enough to be protected. >> >> If you want to be sure your best move is to contact the FSF or a >> lawyer specializing in copyright. >> >> BR, >> >> Benjamin >> >> 2016-07-22 5:00 GMT+02:00 Ch'Gans <chg...@gna.org>: >> > Hi there, >> > >> > I've recently added a "bool FuzzyCompare(float f1, float f2)" function >> > to a proprietary software I'm currently paid to work on (this is plain >> > C++ project, it doesn't use the Qt framework at all). >> > Being a more-than-happy Qt user in my spare time I decided that I >> > would first checkout the qFuzzyCompare implementation since I consider >> > Qt developers as top-of-the-notch C++ wizards (no kidding and no >> > attempt to be nice with them). >> > >> > I have added a comment to "my" implementation referring to the >> > implementation of "qFuzzyCompare" in Qt5 source code (along with [1]). >> > The 2 implementations look alike indeed (apart from using std::fabsf, >> > std::min, etc.. in place of qAbs, qMin, ...), since the fuzzy compare >> > is a well-known algorithm. >> > My reference to Qt5 was there to justify the use of the "magic >> > constant" 100000.f. >> > >> > I was pointed out that there's a potential LGPLv3 license >> > infringement, although I understand where the FUD is coming from, I >> > think that it is OK to read LGPLv3 source code to get inspired as long >> > as you don't blindly copy/paste code (In my case i checked out quite a >> > few articles and forum threads before choosing the Qt way as the best >> > way to do it for my application). >> > >> > So my question is actually very serious, in this particular case, >> > would this be considered as a LGPLv3 infringement of Qt5 to add this >> > to a piece of proprietary software: >> > // Taken from Qt5 source code, see >> > http://doc.qt.io/qt-5/qtglobal.html#qFuzzyCompare-1 and >> > // >> > https://code.woboq.org/qt5/qtbase/src/corelib/global/qglobal.h.html#_ZL13qFuzzyCompareff >> > // And for the insomniacs: >> > >> > https://randomascii.wordpress.com/2012/02/25/comparing-floating-point-numbers-2012-edition/ >> > bool FuzzyCompare(float f1, float f2) >> > { >> > return (::fabsf(f1 - f2) * 100000.0f <= std::min(::fabsf(f1), >> > ::fabsf(f2))); >> > } >> > >> > For comparison purpose, here is the Qt source code: >> > Q_DECL_CONSTEXPR static inline bool qFuzzyCompare(float p1, float p2) >> > { >> > return (qAbs(p1 - p2) * 100000.f <= qMin(qAbs(p1), qAbs(p2))); >> > } >> > >> > You can find many more implementations of this algorithm on >> > stack-overflow and other forums. >> > >> > At the end, I proposed to change the comments to refer to wikipedia >> > instead of Qt5 source code and saying that 100000.0f is the right >> > value for epsilon. >> > >> > I know this is a drop in an ocean (we're talking 1 line of C++), but i >> > think the question is indeed interesting. Thanks for shedding light on >> > this particular issue. >> > >> > Chris >> > >> > >> > [1] >> > https://randomascii.wordpress.com/2012/02/25/comparing-floating-point-numbers-2012-edition/ >> > _______________________________________________ >> > Interest mailing list >> > Interest@qt-project.org >> > http://lists.qt-project.org/mailman/listinfo/interest >> _______________________________________________ >> Interest mailing list >> Interest@qt-project.org >> http://lists.qt-project.org/mailman/listinfo/interest > > _______________________________________________ Interest mailing list Interest@qt-project.org http://lists.qt-project.org/mailman/listinfo/interest
