Wednesday, September 12, 2007


My discussion about open source continues with a look at the LGPL license. When you are modifying large programs, the GPL is quite fair. In the cases of libraries, things are a bit different. A library is a collection of functions that are used to make writing new programs easier. The problem is that if you are using a GPL licensed library, you are using GPL code and have to release your project under the GPL. While one could argue that nothing but development time is forcing you to use that GPL library, some programmers feel that the library should be considered a separate entity from the main program and understand that some people don't want to release their source code. For those people there is the LGPL.

The Lesser General Public License was at one time known as the Library General Public License as the whole purpose of the license was to make it possible for library creators to allow other people to use their libraries in the project without forcing the project into the GPL. This license effectively treats the code within the library as a separate project from the main code. Any changes to the source code of the library are treated like changes to a GPL project. However, the project using the library can be released under any license or even kept as closed source.

The reason that the name was changed from Library to Lesser has to do with Richard Stallman's basic philosophy when it comes to open source software. Richard wants to see everything released under an open license, and as such the LGPL fails as it can be used as part of a closed source project. At the same time people who do use this license tend to do so because they want their source code to be usable by as many programmers as possible while still wanting the code they release to stay open. Some companies won't use GPL code but will use LGPL code so the LGPL programmers do have valid arguments. Likewise, certain types of projects really can benefit financially only if they are closed source so the LGPL allows those developers to at least contribute part of their work to the open source community which would be something they could not financially do if the GPL was their only choice.

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