[PyKDE] Licensing questions

David Boddie david at boddie.org.uk
Mon Jan 8 14:28:13 GMT 2007

On Mon Jan 8 05:31:24 MET 2007, Matt Newell wrote:

> I hope to not confuse the issue, but I think this isn't entirely correct.
> GPL only covers distribution, so if you distribute an application linking
> to commercial Qt, the GPL does not allow linking GPL PyQt against it.
> However, if there is no distribution, then it is perfectly fine.
> For example you(personal or business) are currently using GPL Qt and PyQt,
> then you decide you would like to use some of the features of ActiveQt, so
> you buy a commercial Qt license. It is still fine to use GPL PyQt.
> However if you choose to distribute the software(whether free or for a
> fee), you must then either buy the commercial PyQt, or distribute a version
> that links to the GPL Qt and not provide the ActiveQt functionality.

Bear in mind that this sort of usage, while within the letter of the license,
_might_ get you into trouble with the copyright holder if you later decide
to switch to a commercial license.

For example, a vendor who provides such a dual-license scheme might refuse to
sell you commercial licenses if they suspect that you employed lots of people
to develop a product using their GPL-licensed product then decided to buy a
few commercial licenses to "go legitimate".

I've seen people complain that a vendor would violate the GPL by refusing to
sell commercial licenses in such a case, but they would have the right to
refuse to sell commercial licenses (unless the law prevents that) and does
not affect the rights of the software developer that are granted by the GPL.
The developer is still able to go ahead and release their product under the
GPL but, of course, that's precisely what they want to avoid in such
situations. :-)


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