[Qt-interest] Licensing

[Steven Doerfler]

On 5/29/2010 3:14 PM, Constantin Makshin wrote:
> On Saturday 29 May 2010 22:41:40 Steven Doerfler wrote:
>   
>> On 5/29/2010 2:14 PM, Constantin Makshin wrote:
>>     
>>> On Saturday 29 May 2010 19:36:51 Colin S. Miller wrote:
>>>   
>>>       
>>>> ...
>>>> Assuming that your product is shipped on a CD/DVD,
>>>> then placing the code on the disc is sufficient.
>>>>     
>>>>         
>>> AFAIR, [L]GPL doesn't require distributing the source code along the program/library, they only require that the code can be easily retrieved and the user has related information (how to get the code). And since Qt code is freely available to everyone, Phil can simply put a Qt address (http://qt.nokia.com) somewhere in his program's docs (unless he uses modified version of Qt, of course).
>>>   
>>>       
>> I think if you read the LGPL license, you'll discover that merely
>> including a URL isn't sufficient to comply.  (It's OK only when you're
>> distributing your own software online, and even then, you have to
>> provide your users with the Qt sources from the same place your users
>> get your program.  You can't just point them to Nokia.  See section 6d.)
>>     
> But section 4 says "third parties are not compelled to copy the source along with the object code". I understand this sentence so that developers of closed-source Qt applications don't have to distribute Qt source code (if it wasn't modified) along with their programs, just like developers of GPL software don't have to provide copies of all third-party libraries they use.
>
>   

Look at the whole sentence you're partially quoting:

  If distribution of object code is made by offering access to copy
from a designated place, then offering equivalent access to copy the
source code from the same place satisfies the requirement to
distribute the source code, even though third parties are not
compelled to copy the source along with the object code.

First, the whole sentence is conditional on "If distribution of object
code is made by offering access to copy
from a designated place".  In the above example, the product is shipped
on CD/DVD, not via download.  So this sentence doesn't apply to the example.

Second, note the use of "the same place".  You have to let other people
download the Qt source code from the same place you're distributing any
Qt object code.  If you've got some Qt object code inside your installer
and people can download that from your site, this paragraph says it's
insufficient to just let people get the source from Nokia.  You have to
supply it from "the same place".

The sentence fragment you quoted is saying that, if you

1. Distribute some Qt object code via download from your site, and also
(as required)
2. Let people download Qt source code from your site, then you don't
also have to
3. Force people to download Qt source code whenever they download the Qt
object code.

It might well be sensible and logical for the license to operate the way
you suggested, just letting people download stuff from Nokia, but it
doesn't work that way.

Oh, and finally, the whole of section 4 won't even be useful for typical
commercial Qt programs trying to use Qt under LGPL.  It's for
distributing the library itself, not for distributing a "work that uses
the Library", such as you'd produce by linking your program with Qt. 
Sections 5 and 6 handle those.  You may only apply section 4 if you're
distributing "verbatim copies of the Library's complete source code", or
a modified version that "must itself be a software library", or a
"portion or derivative of it".  So the entire section is inapplicable to
this case.

Steven