| .. _license-discussion: | |
| Licenses | |
| ======== | |
| Matplotlib only uses BSD compatible code. If you bring in code from | |
| another project make sure it has a PSF, BSD, MIT or compatible license | |
| (see the Open Source Initiative `licenses page | |
| <https://opensource.org/licenses>`_ for details on individual | |
| licenses). If it doesn't, you may consider contacting the author and | |
| asking them to relicense it. GPL and LGPL code are not acceptable in | |
| the main code base, though we are considering an alternative way of | |
| distributing L/GPL code through an separate channel, possibly a | |
| toolkit. If you include code, make sure you include a copy of that | |
| code's license in the license directory if the code's license requires | |
| you to distribute the license with it. Non-BSD compatible licenses | |
| are acceptable in Matplotlib toolkits (e.g., basemap), but make sure you | |
| clearly state the licenses you are using. | |
| Why BSD compatible? | |
| ------------------- | |
| The two dominant license variants in the wild are GPL-style and | |
| BSD-style. There are countless other licenses that place specific | |
| restrictions on code reuse, but there is an important difference to be | |
| considered in the GPL and BSD variants. The best known and perhaps | |
| most widely used license is the GPL, which in addition to granting you | |
| full rights to the source code including redistribution, carries with | |
| it an extra obligation. If you use GPL code in your own code, or link | |
| with it, your product must be released under a GPL compatible | |
| license. i.e., you are required to give the source code to other | |
| people and give them the right to redistribute it as well. Many of the | |
| most famous and widely used open source projects are released under | |
| the GPL, including linux, gcc, emacs and sage. | |
| The second major class are the BSD-style licenses (which includes MIT | |
| and the python PSF license). These basically allow you to do whatever | |
| you want with the code: ignore it, include it in your own open source | |
| project, include it in your proprietary product, sell it, | |
| whatever. python itself is released under a BSD compatible license, in | |
| the sense that, quoting from the PSF license page:: | |
| There is no GPL-like "copyleft" restriction. Distributing | |
| binary-only versions of Python, modified or not, is allowed. There | |
| is no requirement to release any of your source code. You can also | |
| write extension modules for Python and provide them only in binary | |
| form. | |
| Famous projects released under a BSD-style license in the permissive | |
| sense of the last paragraph are the BSD operating system, python and | |
| TeX. | |
| There are several reasons why early Matplotlib developers selected a | |
| BSD compatible license. Matplotlib is a python extension, and we | |
| choose a license that was based on the python license (BSD | |
| compatible). Also, we wanted to attract as many users and developers | |
| as possible, and many software companies will not use GPL code in | |
| software they plan to distribute, even those that are highly committed | |
| to open source development, such as `enthought | |
| <https://www.enthought.com>`_, out of legitimate concern that use of the | |
| GPL will "infect" their code base by its viral nature. In effect, they | |
| want to retain the right to release some proprietary code. Companies | |
| and institutions who use Matplotlib often make significant | |
| contributions, because they have the resources to get a job done, even | |
| a boring one. Two of the Matplotlib backends (FLTK and WX) were | |
| contributed by private companies. The final reason behind the | |
| licensing choice is compatibility with the other python extensions for | |
| scientific computing: ipython, numpy, scipy, the enthought tool suite | |
| and python itself are all distributed under BSD compatible licenses. | |