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The problem isn't dynamic linking, its the requirement that the end user must be able to re-link a modified version of the LGPL code. So for example, the user s

The problem isn't dynamic linking, its the requirement that the end user must be able to re-link a modified version of the LGPL code. So for example, the user should be able to replace the Qt libraries your application links to. On closed platforms like iOS and Android (on Google Play) this isn't really possible. How would your user access your application, modify it and re-sign it?

shawn-butler 11y ago
Previous discussion on HN of the mail app Sparrow and their approach in complying with LGPL on iOS: https://news.ycombinator.com/item?id=4302517 https://news.ycombinator.com/item?id=4302517 May be helpful to you.
- twqtisgreatbut 11y ago
  Its not helpful, they aren't complying with the relinking clause. I don't think there's any way to use LGPL with closed source on mobile app stores.
  - shawn-butler 11y ago
    I'm assuming you didn't read it. I will give you benefit of the doubt since the Sparrow page was pulled after Google acquired them. Sparrow made available on a website the necessary binaries for the user to relink if they so chose thus complying with the terms of LGPL.
CamperBob2 11y ago
Presumably your closed-source library has an API that you can document. This is how I handle some hardware-access DLLs for proprietary hardware; the distribution gives you the full source for the main program and the non-proprietary hardware access modules, plus the .DLL with the secret sauce for my own hardware. When you run the app, it loads all of the API-compliant DLLs and adds them to the device-selection menu. Anyone can build their own .DLL with the header files provided, or recompile the existing "open" ones if desired. For an iOS project, you'd provide a link to the GitHub/Sourceforge page or whatever. It's true that the end user would have to get a signing key from Apple to exercise their rights under the LGPL, but IMHO that still meets the spirit of the law. As far as I'm concerned my obligation ends when I provide the code. Some will disagree (hence GPLv3), but the same problem would exist if I had used a language (or targeted a platform) for which there were no free compilers, and nobody seems to have a problem there.

shawn-butler 11y ago

Previous discussion on HN of the mail app Sparrow and their approach in complying with LGPL on iOS: https://news.ycombinator.com/item?id=4302517 https://news.ycombinator.com/item?id=4302517 May be helpful to you.

twqtisgreatbut 11y ago
Its not helpful, they aren't complying with the relinking clause. I don't think there's any way to use LGPL with closed source on mobile app stores.
- shawn-butler 11y ago
  I'm assuming you didn't read it. I will give you benefit of the doubt since the Sparrow page was pulled after Google acquired them. Sparrow made available on a website the necessary binaries for the user to relink if they so chose thus complying with the terms of LGPL.

CamperBob2 11y ago

Presumably your closed-source library has an API that you can document. This is how I handle some hardware-access DLLs for proprietary hardware; the distribution gives you the full source for the main program and the non-proprietary hardware access modules, plus the .DLL with the secret sauce for my own hardware. When you run the app, it loads all of the API-compliant DLLs and adds them to the device-selection menu. Anyone can build their own .DLL with the header files provided, or recompile the existing "open" ones if desired. For an iOS project, you'd provide a link to the GitHub/Sourceforge page or whatever. It's true that the end user would have to get a signing key from Apple to exercise their rights under the LGPL, but IMHO that still meets the spirit of the law. As far as I'm concerned my obligation ends when I provide the code. Some will disagree (hence GPLv3), but the same problem would exist if I had used a language (or targeted a platform) for which there were no free compilers, and nobody seems to have a problem there.