Author Topic: Newb question about LGPL license (Read 11573 times)

retrogamer4ever · « **on:** May 08, 2009, 09:03:10 pm »

Hey there I was wondering if some one could explain to me the whole deal with the LGPL, I read up on it and it's just so much to take in... What I have taken from it is that you can use the code for both open source and commercial as long as you share your code? Now that is what I am confused on... So if I dynamically link the code and don't tinker with any of the source, does that mean I still need to share all of my projects source code to the world simply because I am using that library? Or does it mean if I tinker with the source of the library under LGPL then I have to share the code I tweaked.

I have a commercial project I want to start but I don't want to share my projects code and I don't plan to tweak any of the libraries I have implemented that are under that license... Do I still have to share ALL my code? I have no problem sharing any tweaks I make to library if I make them.

So many different licenses it can all get very confusing... At least for me anyways, an explanation would be greatly appreciated!

retrogamer4ever · « **Reply #1 on:** May 09, 2009, 07:33:55 am »

I see, so as long as I have those .dll files in there and I don't modify the source I don't have to share my projects source code?

Groogy · « **Reply #2 on:** May 09, 2009, 10:59:32 am »

Quote from: "retrogamer4ever"

I see, so as long as I have those .dll files in there and I don't modify the source I don't have to share my projects source code?

Yah pretty much. Depending on what license you use yourself. Though I don't know if you have to provide a text file with the LGPL conditions which only applies to the SFML libraries?

Anyway, you do know that Open Source can still be commercial. You can sell your product but still give them the source code with the binary. Though you'll have to do some tweaking with the license agreement or use one of the already done.

Dig · « **Reply #3 on:** May 09, 2009, 11:46:49 pm »

SFML is licensed under the zlib/png license which is a lot more permissive than the LGPL.

My understanding:
The LGPL only requires you to release changes you make to the LGPL licensed code IF you dynamically link to the code. You need to released ALL your source code under the LGPL or GPL if you statically link to LGPL libraries.

The simple idea being that end users can take advantage of updates to the LGPL licensed library either by replacing the dynamic libraries with new version or by recompiling with the source you've provided.

Not sure if that makes things clearer or not!

retrogamer4ever · « **Reply #4 on:** May 10, 2009, 12:14:26 am »

Yeah it did :-D It's all very clear now! Thanks for the explanation everyone, it was very helpful :-)

nitram_cero · « **Reply #5 on:** May 10, 2009, 04:24:32 am »

Notice that even thou SFML has a zlib license, it depends on other LGPL licenced libraries to work, like OpenAL and libsndfile.

So you can't statically link to those. You don't have to worry about doing so as all configurations for SFML don't do it... but just remember to send the dlls of those with your games!

-Martín

drpitch · « **Reply #6 on:** June 02, 2009, 11:51:56 pm »

Hi all

I also have a question about LGPL licence: I'm developing a commercial project that runs on a computer with wacom touchscreen, so I had to modify SFML to add touchscreen support. So now I need to share the source code of my commercial project?

Thanks!

nfries88 · « **Reply #7 on:** June 03, 2009, 01:12:41 am »

Quote from: "drpitch"

Hi all

I also have a question about LGPL licence: I'm developing a commercial project that runs on a computer with wacom touchscreen, so I had to modify SFML to add touchscreen support. So now I need to share the source code of my commercial project?

Thanks!

Only your modifications to SFML.
And if the wacom touchscreen is a widely used piece of equipment it very well may be much appreciated (and, who knows, SFML developers may be able to improve your code, so the improvement can get back to you too).

That's the one beauty of open source.

drpitch · « **Reply #8 on:** June 03, 2009, 01:37:11 am »

Thanks for your answer.
I'll glady share the source. I hope my changes can be useful to anyone

Laurent · « **Reply #9 on:** June 03, 2009, 07:39:12 am »

Quote

Only your modifications to SFML.

No, if you want to keep it for you the zlib/png license allows it

drpitch · « **Reply #10 on:** June 03, 2009, 11:20:28 am »

Thanks to clear it up. Anyway, my concern was whether I was required to distribute the sources of the commercial project or not. I have no problem sharing any changes I make to library if this helps to the community

nfries88 · « **Reply #11 on:** June 04, 2009, 03:08:25 am »

Quote from: "Laurent"

Quote
Only your modifications to SFML.

No, if you want to keep it for you the zlib/png license allows it

Oh yeah, I keep forgetting that the SFML is under a friendlier license. xD

gsaurus · « **Reply #12 on:** January 12, 2010, 11:02:04 am »

Quote from: "Wavesonics"

You *can* use LGPL libraries in a commercial project as long as you only dynamically link to the library. But the moment you statically link to LGPL code your code automagically becomes LGPL and must be open sourced, isn't that nice of them

Does that apply to GPL too? Or is that what differs from LGPL to GPL?

Edit: ok, this answers my question:

Quote

The main difference between the GPL and the LGPL is that the latter can be linked to (in the case of a library, 'used by') a non-(L)GPLed program, regardless of whether it is free software or proprietary software.

panithadrum · « **Reply #13 on:** January 12, 2010, 07:42:35 pm »

Hmm Anyone really cares about that? I think licenses are like a giant dark ball of sh*t, just drives me crazy and confused

Is someone going to check what you use and what licenses are you breaking?

pdusen · « **Reply #14 on:** January 18, 2010, 04:42:49 pm »

Quote from: "panithadrum"

Hmm Anyone really cares about that? I think licenses are like a giant dark ball of sh*t, just drives me crazy and confused

Is someone going to check what you use and what licenses are you breaking?

Some organizations make a tidy business of doing just that. For example, http://en.wikipedia.org/wiki/Software_Freedom_Law_Center