Lgpl

#1 You might want to browse around on the GNU site (www.gnu.org) for a more helpful interpretation.

#2 Thanks for that, but I still can't make clear sense of it. There seems to be a pretty vague part to do with the way you link to the library. One way, you can release it any way you like, the other, I think you have to apply the LGPL to the entire work that uses the library. But like I said, I'm not clear on it, and I may be wrong.

Does anyone have any experience with using LGPL'd libraries?

#3 You only have to apply the LGPL to it all if you dont dynamically link (i.e. dont use a dll)

#4 @Tim: not true. In fact, the only method you can use a lgpled library is by dynamically linking. If you were to statically link to it, by default your entire executable would have to be released under the GPL license.

Quote:
However, linking a "work that uses the Library" with the Library creates an executable that is a derivative of the Library (because it contains portions of the Library), rather than a "work that uses the library". The executable is therefore covered by this License. Section 6 states terms for distribution of such executables.

@Willam: If you modify the library, then you must include your source to the library when you release along with a copy of the lgpl, or a place where your changes can be downloaded with a notice of that in your release. If you do not modify the library, but simply link to it, then you don't have to do anything.
Although including a text file with the place you got the library from and who wrote the library is a "good thing".

#5 @NfoCipher: The reply you said to Tim is just said he said. I think you mis-read his post.


Anyway, Tim and NfoCipher are correct about what you have to do if using it dynamically or statically. About

Quote:
Although including a text file with the place you got the library from and who wrote the library is a "good thing".

You don't need to. Simply giving credit to the library's author in your credits part of your game/program would be enough along with the URL homepage of the library and/or name of the library would also be a big help to others. Something like:

by
URL:

or whatever better fits your games'/program's credits.


If you redistribute the library then I recommend that you do in fact keep the LGPL license information along with it(like what NfoCipher recommended above). For information in the text file I would name it DeviL_Info.txt with something like:

by
Homepage at
Date/Version

LGPL License:



Simple huh? You'll get use to working with Open Source licenses and rest which isn't bad really.

#6 Legally you MUST include a copy of the LGPL text itself with the library (whether you modify it or not), so if the library is included in your game, the LGPL must be as well (but the rest of your game does not need to be GPL/LGPL). Keep in mind, though, there's no requirement to make the LGPL text particularly visible, so just including it in the directory you install the game files is enough, you don't have to add a shortcut to it from the Start/Programs menu or anything (assuming you are distributing a Windows game), etc. I mention this only because the LGPL can be very confusing when end users read it and think it applies to them (which technically it does, but how many of them are really going to be programmers interested in modifying the source?).

Legally you also must make a copy of the source (of the LPGL library only, not the rest of your game/app) available to anyone who asks for it, even if you haven't changed the library. The FSF's policy is that simply giving users who ask for a copy of the source a link to the library's main site is not enough, you must actually provide the source. This isn't as bad as it sounds, you don't have to offer the source via the net, you can offer it on CD and charge a "reasonable fee" of say $20 to anyone who wants a copy. From a practical standpoint, nobody will ever ask for a copy unless you've made (very useful) changes to the code.

The short version of the above is that not making any changes to the library doesn't nullify your need to include the LGPL text or offer source if asked for it. To a certain degree this is a non-issue practically because most LGPL library authors won't really care if you adhere to the letter of the LGPL as long as you haven't made useful changes to the base library, but if you want to be fully legal keep in mind that not changing the source doesn't mean you have to do "nothing".

#7 Thanks very much everyone, that was exactly what I was after :)

I don't mind at all including the license with the library, and crediting the homepage, and even offering the source is no great problem. Just wanted to be sure that everything was legit before I released it on the web. Thanks again.