On Sunday 11 November 2007 08:55:51 Shriramana Sharma wrote: > The question is not whether a work *includes* parts of Qt or not. The > very fact that it is dependent on Qt for its functioning makes it a > derivative work, and it *must* be licensed under the GPL when > distributed, whether in source form or compiled form. #include <some_library> does not make my C++ source code a derivative work of some_library. If I write source code that uses a library, that does not make the source code a dervitive of the library. I am under absolutely no obligation to follow the license of the library, whatever it may be, if I don't distribute it. I can release my own source code -- no matter what that source code theoretically describes -- under any license I want, as I am the sole copyright holder. Now, if I compile my program, and link it against a library, the resulting binary is (in most circumstances) a derivative work of both the library and my source code. Now, if I want to distribute this result, I've got to follow the license of the library, as I have created a derivitive work. For example, I can write completely proprietary[1] programs that use Qt. I can distribute the source code under any license I want. Others that I gave/sold my source code to could compile and use my proprietary program with GPL Qt. But I (and they) can't distribute a precompiled binary of my program as it (in most circumstances) would be a derivative work of Qt. To give some context: sometimes [often?] the problem that distributors (like Debian) have is that a given program may be completely free software as distributed upstream -- all of the program code and libraries it uses are free software independently, but because of license incompatibilities, binaries end up being undistributable because they are derivitive works of several licenses with incompatible requirements. Footnotes: [1] Or BSD, or GPLv3, or Apache, or ... -- Wesley J. Landaker <wjl@icecavern.net> <xmpp:wjl@icecavern.net> OpenPGP FP: 4135 2A3B 4726 ACC5 9094 0097 F0A9 8A4C 4CD6 E3D2
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