[SciPy-user] licence: GNU or not GNU for new image analysis platform

Fernando Perez Fernando.Perez at colorado.edu
Fri Sep 16 16:11:44 CDT 2005

Sebastian Haase wrote:

> Now: before I can give this to anyone my university requires me to attach a 
> license to this. I think I like the "copyleft" idea of GPL or maybe better 
> LGPL.  
> My understanding is that this would allow a company to sell it, but they would 
> have "make their changes publicly available" (under LGPL again)
> I think Fernando's IPython is LGPL  - and I think my "platform" is quite a 
> similar spirit...

Nope, BSD as well.  It used to be LGPL, but I changed to BSD a year ago.  My 
reasoning was multiple-fold (I'm speaking for myself here, NOT for Prabhu):

- Python itself is BSD-like.  I'd rather have a license that's as 
python-compatible as possible.

- It lowers the 'barrier to adoption', since some people/institutions have 
blanket no-GPL policies.

- scipy is BSD, and I like scipy :)  More seriously, ipython is so heavily 
used by scipy users, that I wanted to harmonize with it as much as possible.

- matplotlib is BSD, and I also want very tight integration with matplotlib. 
Compatible licenses make this much easier.

- Even if this opens the possibility of someone 'stealing' ipython, I don't 
care.  I suspect that in the long run, it's more beneficial for people who may 
use it to contribute back their changes.

There is a substantial cost in maintaining a branched copy of a project 
without contributing, because the burden of integrating the project's mainline 
development falls on you.  Unless you are trying to flat out fork a project, 
in most cases it's easier to just send your changes back to the mainline.

- John Hunter's experience with matplotlib supports that last point: he's had 
private companies contribute back mpl enhancements, simply because it's not 
worth their time to keep them separate and have to manually track matplotlib 
in a private branch.

You can see the original messages on this in the ipython lists:


I sent these to everyone who had ever contributed to ipython, and got no 
negative replies, so I didn't have to rewrite any code myself (though I was 
prepared to if I had to).

I think there is a place for the GPL, and I'm not fundamentally anti-GPL.  But 
in my case, I felt the benefits of a BSD approach were significant, and I went 
with it.

Ultimately the decsion is yours, though keep in mind that given that scipy, 
mayavi, matplotlib, ipython (and the new wx-based graphical ipython) are all 
BSD, the room for integration with other tools for your project will grow with 
BSD.  A *GPL license will to some extent 'wall off' your project from these 
others.  The decision of what to do is fully yours.



ps - Just to be clear: I am NOT engaging into a license discussion/war.  I 
won't reply to any message in that direction.  I was simply clarifying for 
Sebastian's benefit the reasoning behind ipython's licensing, since he was 
under the impression (historically correct, but currently not anymore) that 
ipython was LGPL.  If you feel very strongly about this topic, there are many 
places on the net where you can discuss it.

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