On Fri, 2012-08-17 at 13:06 +0100, Joseph Rushton Wakeling wrote: > On 17/08/12 08:55, Russel Winder wrote: > > Can I suggest a re-phasing "proprietary code needs to dynamically link > > to Qt to comply with the LGPL". To avoid the LGPL with Qt you need to > > buy a commercial Qt licence. > > I think this is over-stating the licence requirements. The legally safest > option is certainly to dynamically link against the LGPL-licensed code, but > it's > not an explicitly-stated _requirement_ of the licence.
This is true. About a decade ago I took legal advice regarding GPL, LGPL and various scenarios. The problem was that there was very little case law to give solidity to any interpretation of the licences and the law surrounding them. Taking a defensive view is thus the safest way forward. > The requirements are that the recipient of the program must be able to link > it > to a newer version of the LGPL-licensed part. That could be achieved through > dynamic linking, or it could be achieved through distributing object files > along > with the program. (You could also distribute source code, but since this is > what's trying to be avoided here it's not a solution.) We also thought about this interpretation of compliance, but it leads to dangerous doubts for end user products. OK for software tools where the end user is themselves in the software business. > Qt recommends dynamic linking because it can't be guaranteed that some legal > jurisdictions wouldn't interpret a statically-linked program as a "derivative > work" of the LGPL-licensed code, thus falling under its copyleft provisions. > However, such an interpretation is almost certainly not in line with the > licence's intentions. The core problem here is no case law and no international agreements. So "derivative work", "linking", "dynamic" and "static" are all legally undefined in this contexts in many jurisdictions. Worse I bet there are very few computer literate folk working in jurisprudence. > It might be worth contacting the Software Freedom Law Center for advice on > these > points: https://www.softwarefreedom.org/ But the problem is that they are USA centric. Or are they taking on more people internationally now? -- Russel. ============================================================================= Dr Russel Winder t: +44 20 7585 2200 voip: sip:russel.win...@ekiga.net 41 Buckmaster Road m: +44 7770 465 077 xmpp: rus...@winder.org.uk London SW11 1EN, UK w: www.russel.org.uk skype: russel_winder
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