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The GNU General Public License (GPL) and GNU Lesser General Public License (LGPL) contain many additional restrictions to the concept of copyleft, and are very misunderstood, over-hyped, and don’t maintain compatibility with newer versions. Even the LGPL is reportedly problematic
The GPL and LGPL are of more political nature than other similar FOSS licences, and as such should be avoided. I recommend using the Sleepycat licence, which is a strong-copyleft licence, that is compatible with GPLv2 and above, instead of the GPL and the MPL 2.0 (or above) licence instead of the LGPL. Naturally, permissive, non-copyleft, open-source licences such as the MIT Expat License are an option. What the Sleepycat licence says is that code distributed under it, must remain under it, and that one must release the source code for publicly-distributed binaries that link against it. However, from my understanding, as opposed to the GPL, this source code doesn’t have to be completely free. It doesn’t have the additional restrictions on licences’ compatibility that the GPL has, nor does it have the other obscure and not-well-understood restrictions that the GPL has.
I read the GPLv2 originally once and couldn’t understand it. The LGPLv2 or the GPLv3 would likely prove to be more problematic. I find it harder to trust lengthy documents that I am unable to understand. I had no problem understanding the Sleepycat licence, the Artistic 2.0 licence, or the Expat and BSD licences, so I can better recommend them instead.
One fact I should note is that the GPL often stands against the Hacker’s attitude as presented by Eric Raymond in the document “How to become a Hacker”. It states that:
The world is full of fascinating problems waiting to be solved.
No problem should ever have to be solved twice.
For example, the Free Software Foundation now started the GNU PDF project that is licensed under the GPL version 3, because all the other Free software PDF projects are GPL version 2 only. So because the GPL was used, the same problem need to be solved twice.
Another case where it happened was this story of an the Inkscape set operations patch:
Once before, someone had contributed a patch to add boolean operations, but that patch relied on a polygon clipping library provided under an incompatible license. There’s little more frustrating than having a solution in hand, only to be hamstrung by legal problems. Even though it was an important feature for us, we regretfully postponed development of it into the distant future on our roadmap and proceeded with other work.
Furthermore, the OpenBSD project are now re-implementing a lot of software that is only available as GPL or similar licences, under BSD-style licences, due to OpenBSD’s stricter licensing policy.
And finally, often one can build upon non-GPL-like-code and not release the derived work as free and open source software, without it causing any harm, and actually causing a lot of good. Which is otherwise prevented if the code is GPLed.