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The open source version of Qt is LGPL, which basically means you may use it in a proprietary application if you use dynamic linking. If you link statically or c

The open source version of Qt is LGPL, which basically means you may use it in a proprietary application if you use dynamic linking. If you link statically or copy any of its code, then your program must be free software (GPL). If you pay for a commercial license, you can link statically without restriction. The commercial version is also necessary for locked-down platforms like iOS where the dynamic linking can't be changed by the end user of the software. IANAL, and there are a few details I glossed over, but that's the simple version.

Nokinside 10y ago
Either dynamic linking or provide object files that can be linked with the library. In essence, you can use it in proprietary application as long as you don't modify the library and you provide means to switch to different version of the library.
donatj 10y ago
If I statically link is my code inherintly LGPL or could I still license MIT?
- int_19h 10y ago
  If LGPL was "viral" even when linking dynamically, there would be no point in it (it'd be like GPL). So, yes. You can use MIT. Of course, the dynamic dependency still remains LGPL.
  - kuschku 10y ago
    Yes and no. LGPL only is non-viral if the end user can trivially replace the linked library with their own version.
hurd 10y ago
"If you link statically or copy any of its code, then your program must be free software (GPL)." I don't the first part is true (the second one is though). https://www.gnu.org/licenses/gpl-faq.en.html#LGPLStaticVsDynamic https://www.gnu.org/licenses/gpl-faq.en.html#LGPLStaticVsDyn...
- slavik81 10y ago
  The second part isn't technically true either. You can copy code without requiring a license if you meet the requirements for fair use. For example, copying function signatures for interoperability. I was trying to be conservative and paint a simplified picture of the license that you can't go wrong by following, but I definitely erred in leaving out some possibilities and presenting it as if they don't exist.

Nokinside 10y ago

Either dynamic linking or provide object files that can be linked with the library. In essence, you can use it in proprietary application as long as you don't modify the library and you provide means to switch to different version of the library.

donatj 10y ago

If I statically link is my code inherintly LGPL or could I still license MIT?

int_19h 10y ago
If LGPL was "viral" even when linking dynamically, there would be no point in it (it'd be like GPL). So, yes. You can use MIT. Of course, the dynamic dependency still remains LGPL.
- kuschku 10y ago
  Yes and no. LGPL only is non-viral if the end user can trivially replace the linked library with their own version.

hurd 10y ago

"If you link statically or copy any of its code, then your program must be free software (GPL)." I don't the first part is true (the second one is though). https://www.gnu.org/licenses/gpl-faq.en.html#LGPLStaticVsDynamic https://www.gnu.org/licenses/gpl-faq.en.html#LGPLStaticVsDyn...

slavik81 10y ago
The second part isn't technically true either. You can copy code without requiring a license if you meet the requirements for fair use. For example, copying function signatures for interoperability. I was trying to be conservative and paint a simplified picture of the license that you can't go wrong by following, but I definitely erred in leaving out some possibilities and presenting it as if they don't exist.