[Qt-interest] Some questions about LGPL licensing

[Konrad Rosenbaum]

Hi,

IANAL

First off: it is usually not a good idea to link Qt statically - it uses a 
lot of dynamic code (plugins) that runs better in a fully dynamic 
environment. And since you probably pre-package the program into an 
installation package anyway it shouldn't matter whether the executable is 
one file or a dozen files.

On Tuesday 21 April 2009, RFOG wrote:
> Can I statically link a program with source code available? That is a
> program that is not covered by any licence other than "do with it all
> you want" but it comes with source code -and project files- compressed
> in same ZIP file that cotains the executable. We offer this way our
> demo sample programs to show how to use our devices with code.

Yes, possible. Ideally the ZIP should also contain the Qt sources or at 
least at a prominent place a link where to download Qt.

> Can I statically link a propietary program given as free? We offer
> some other programs as free but without source code available,
> basically they are programs that works with our devices to configure
> or test them.

Free as in beer? Cost does not matter to the LGPL, freedom does.

You have to offer your users the possibility to link the program against a 
newer version of the library. There are three possibilities:
a) give them the source
b) use DLLs that can be exchanged at runtime (default with Qt)
c) give them the compiled object files, so that they can redo the linker run

> Can I statically link a propietary program to be sold and, of course,
> no source code available or bein sold in any way? This is just for
> curiosity.

Same three possibilities as above.

> Of course, with dynamic linking all the above questions are allowed,
> but sometimes customers see the runtimes as an inconvenient.

As said earlier: you probably want to create an installation package anyway 
and it does not matter how many files it produces as long as it works.



	Konrad


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