A few lgpl license questions



  • hopefully this topic can help you decide if the lgpl or the commercial license is right for you.

    at this link http://blog.qt.nokia.com/2009/11/30/qt-making-the-right-licensing-decision/ i don't understand a paragraph about lgpl license
    [quote] If you are shipping an executable, you must include any data and utility programs needed for reproducing the executable (i.e. must provide components needed to recompile with a new version of the library) unless such data and utility programs are normally distributed with the major components of the operating system on which the executable runs [/quote]

    is the above talking about my exe program that I would release to the pubic? what are the data and utility programs needed for reproducing the exe file.

    I can't seem to find the answer at the forum about this question. When I distribute my dynamic program, can I include the qt dlls in the same archive along with the source to those dlls or do I need to make the dlls available in a separate package? Edit: I found the answer to this question. I can include the dlls in the archive package


  • Moderators

    Did you check out the numerous postings with respect "licensing?":http://developer.qt.nokia.com/search/tag/license
    That is an ever returning topic.
    Propably you need to concentrate on the second part, I guess. But I am no lawyer, just an engineer :-) So, this is just my humble opinion.
    It would be depending on the machine and OS you are targeting.



  • yes i searched the forum very carefully. in regards to the lgpl license is that i can include the dlls in my dynamic program package and without the source code if i choose.

    also, in my first post, the quoted paragraph, i could not find the answer for. can someone explain what this means?


  • Moderators

    Sorry, lost the point in my last reply. When referring to second part, I have meant the quote you have in your post. That part is:
    [quote author="kalster" date="1311996723"]
    [quote] ... unless such data and utility programs are normally distributed with the major components of the operating system on which the executable runs [/quote]
    [/quote]
    For linux for example, haven't you in most distributions Qt libs and also compiler included? At least there it seems to be easy.



  • [quote author="koahnig" date="1312018414"]...
    For linux for example, haven't you in most distributions Qt libs and also compiler included? At least there it seems to be easy. [/quote]

    The compiler? depens on the version, but gcc may be included. Qtz is only included, if you have KDE, for gnome, AFAIK it's not included by default.

    bq. If you are shipping an executable, you must include any data and utility programs needed for reproducing the executable (i.e. must provide components needed to recompile with a new version of the library) unless such data and utility programs are normally distributed with the major components of the operating system on which the executable runs

    This is exactly why the company I work for decided not to use LGPL licenses, as it's not 100% clear. Even our lawers are not 100% sure, whether that could be meants as giving source out if someone wants to use another qt version so he can recompile our stuff. AFAIK there are no decisions made by lawers up to now about that.

    You will never find a defenit answer about this topic in a comunity forum, as it's difficult law stuff and each lawer will give you a different answer.



  • I think this part of the LGPL should prevent people from "protecting" their published source code by having the prerequisite that the code has to go through some kind of preprocessing tool (like Qt's meta object compiler) which is kept closed source.

    To me it reads "... you have to publish source code changes ... and make sure that everyone has access to the tools required to compile this changes ...".

    I've never seen a project containing LGPL code beeing distributed with a whole compiler suite. As long as all the tools required to build your code changes are freely available (and the Qt SDK is) you should be on the safe side.

    However, IANAL!


  • Moderators

    [quote author="Gerolf" date="1312025472"]
    The compiler? depens on the version, but gcc may be included. Qtz is only included, if you have KDE, for gnome, AFAIK it's not included by default.
    [/quote]
    We could end up discussing what means included. An Ubuntu Linux is using Gnome by default and you can install gcc and Qt.

    Here is Lucas' quote updated to:
    [quote author="Lukas Geyer" date="1312049641"]To me it reads "... you have to publish source code changes to Qt libraries ... and make sure that everyone has access to the tools required to compile this changes ...".
    [/quote]
    This would fit with the "Handy reference chart" on the page with the link provided by kalster.

    BTW the link is broken. The comma should not be part of the link.



  • [quote author="koahnig" date="1312052469"]BTW the link is broken. The comma should not be part of the link. [/quote]

    fixed



  • referring back to the link at the top of this topic. here is another paragraph that talks about source code.

    [quote]Users can develop proprietary applications that dynamically link to the Qt libraries without having to release their application source code.[/quote]

    this paragraph is basically easy to understand. we do not need to include the source code for our dynamic programs.



  • I am new to Qt and not sure how to organize my code so to use dynamic libraries within my own application.

    Would anyone be able to provide an outline of a series of steps I would need to follow?

    Let us suppose I am developing my own application using Qt. How do I dynamically link to the Qt libraries?

    Many Thanks


  • Moderators

    [quote author="maxg0" date="1379327400"]I am new Qt and not sure how to organize my code so to use dynamic libraries within my own application.

    Would anyone be able to provide an outline of a series of steps I would need to follow?

    Let us suppose I am developing my own application using Qt. How do I dynamically link to the Qt libraries?

    Many Thanks
    [/quote]

    Using one of the SDKs on the top of the "download page":http://qt-project.org/downloads you do this automatically.

    If you install the SDK with MinGW you get an IDE (Qt Creator), the compiler suite MinGW and Qt libs already prebuild for dynamic linking.
    If you are creating a project with one of the template projects in Qt creator, you are linking automatically against dlls.
    For deploying to another computer you have to check the steps in "this note.":http://qt-project.org/doc/qt-5.0/qtdoc/deployment-windows.html


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