[Qt-interest] LGPL and static linking

[Thiago Macieira]

Em Terça-feira 01 Dezembro 2009, às 17:42:58, Christian Dähn escreveu:
> Thanks for your answer. It would be great, if I wouldn't have the
> problems of using static binaries and if the performance optimizations
> of the new QtScript module weren't needed.
> 
> Summing up the Qt toolkit was changed in a way where longterm
> commercial customers get problems with open source licenses and
> nobody took care of that.

QtWebkit, QtMultimedia, QtHelp and Phonon have always been LGPL. That position 
has not changed. If your application didn't use them before these modules 
existed (pre 4.4), then nothing would change for you. You'd only need to 
follow the new obligations if you *started* making use of these modules.

The only thing that did change was QtScript. We discussed quite extensively 
internally whether we should do the change. That is, unlike the modules above, 
QtScript was originally dual-licensed under the Commercial license too. So 
this change means your existing app is impacted.

We in the end decided that we don't have the resources to maintain the 
QtScript old engine, while there's a much better one we can use and contribute 
to. We were not going to catch up with SquirrelFish.

> Such was completely incredible in the past - where Qt was developed
> by Trolltech - not by Nokia.

Not really. All of the modules above, aside from QtScript, were introduced to 
Qt while Trolltech was an independent company. The idea of merging the 
scripting engines was also considered before the merger.

The merger only made the decision easier.

Where does this leave you?
1) Don't use the LGPL modules (alternatively use QtScriptClassic)
2) Use them with dynamic linking
3) Use them under static linking, but find respecting the terms of the LGPL

I posted our lawyer's reading of the LGPL. Your lawyer may differ in that 
interpretation, though, which would allow you to ship a statically-linked 
binary. (The "supply the .o files" possibility)

Other than that, I'm not sure I can help you. This change was done for the 
greater good of Qt and the community and it's regrettable that not all can 
move along with us.

-- 
Thiago Macieira - thiago (AT) macieira.info - thiago (AT) kde.org
  Senior Product Manager - Nokia, Qt Development Frameworks
      PGP/GPG: 0x6EF45358; fingerprint:
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