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Thread: LGPL meaning

  1. #1
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    Default LGPL meaning

    Hi there

    I'm confused about licencing. If i get the LGPL version of Qt, can i develop closed applications with it ?
    Do it applies only to dynamic linking, or do it applies to static linking too ?

    Thanks

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    Default Re: LGPL meaning

    Last edited by tbscope; 15th November 2010 at 10:22.

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    Default Re: LGPL meaning

    Although we can say it most definitely does not allow you to create statically linked applications with the LGPL license. Those kind of applications will require a commercial license as you are effectively embedding Qt into your own application.

    For advice beyond that (and the reasons why), you need to contact a lawyer, as tbscope has stated.

    We are not a legal team. We can not offer legal advice.

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    Default Re: LGPL meaning

    Quote Originally Posted by squidge View Post
    Although we can say it most definitely does not allow you to create statically linked applications with the LGPL license. Those kind of applications will require a commercial license as you are effectively embedding Qt into your own application.
    Of course if your program is released using an LGPL compatible license there is no problem with static linking. (I know the question was about closed source applications, but just to get this clear )
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    Default Re: LGPL meaning

    Quote Originally Posted by squidge View Post
    Although we can say it most definitely does not allow you to create statically linked applications with the LGPL license.
    That's not true. There is a clause that lets you link statically an LGPL component to a closed-source application. You need to provide object code (*.o or *.obj, depending on the compiler) for your program so that the end user can relink it back to a working executable. Such a solution is rarely useful (it's much easier to link dynamically and make it harder to break into the application) but it's doable.
    Last edited by wysota; 16th November 2010 at 00:24. Reason: My spelling sometimes really sucks...
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    Default Re: LGPL meaning

    Thanks for the heads up. It shows why we can't give legal advice on a public forum. Different people interpret it differently.

    (I assumed it was not permissable to have Qt as an integral part of your application without commercial license. I was wrong)

    Bottom line: If you don't want to be sued, then talk to a lawyer about the license. At least then, if they get it wrong, you can sue them

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