Open Source License Question

Robert Kern rkern at
Sat Oct 30 05:32:21 CEST 2004

Donnal Walter wrote:


> 1. Is there a compelling reason for PA *not* to use a CL license (say 
> Gnu GPL) for OApps and BigApp? These are "end-user" applications, not 
> system components.

Not terribly compelling to my mind, but:
Some people avoid copylefted works out of (pick one or more: habit, 
ignorance, irrational fear, rational avoidance of licensing 
complexity/uncertainty, any number of things I can't think of off the 
top of my head). CApp authors will almost assuredly use OApps as 
examples for using the framework. A license like the GPL for BigApp 
could limit which CApps you can include because of incompatibilities.

> 2. Am I right in thinking that the license for FW will have little or no 
> legal bearing on the licenses contributors choose for CApps?

If the license you use for the framework is strong copylefted (e.g. GPL) 
as opposed to weak copylefted (e.g. LGPL), then the license *will* have 
a strong bearing on the license used for contributed apps.

> 3. Am I right in thinking that a CL license for BigApp would encourage
> (but not require?) using CL for CApps (if they want them included)?

*shrug* I think that strongly depends on the community that you build 
around your software. If I'm not involved in the community, I'm more 
likely to choose a license for my apps which is in my best 
interests/desires and meets the requirements of the licenses of the 
libraries I am using. Only if there is a strong community that pushes 
for a particular license am I likely to deviate from that preference. 
BigApp's license alone wouldn't do that for me.

> 4. Will either a CL or NCL license for FW affect the likelihood of 
> receiving improvements from programmers outside the field of interest?

Probably, but I would doubt that anyone can tell you how either choice 
will affect contributions. Many people will come up with arguments for 
either position ("GPL will drive programmers away!" "GPL will gives 
programmers assurance that everyone will give back to the community!"). 
Ignore them. They know less than you.

> 5. If PA chooses a CL license for FW, can it later be changed to NCL in 
> order to be combined with FW2?

If you not only are the principal author but also the sole copyright 
owner, then yes. If you fold in changes from other people without having 
them assign copyright to you or have them license those changes under a 
permissive license (BSD, MIT, PSF, and the like), then you must obtain 
permission to relicense from each of them. This can be a problem sometimes.

> 6. If PA choses a NCL license for FW, can it later be changed to CL in 
> order to be combined with FW3?

Similar answer as above. If the non-copyleft license is permissive like 
BSD, etc. then your headaches are greatly reduced.


Robert Kern
rkern at

"In the fields of hell where the grass grows high
  Are the graves of dreams allowed to die."
   -- Richard Harter

More information about the Python-list mailing list