[development] Modules that integrate non-GPL PHP apps violate the GPL.

[Jeff Eaton]

On Aug 31, 2007, at 11:43 AM, ttw+drupal at cobbled.net wrote:

> i think the original author is confused about the exact status of GPL,
> especially, in relation to something like hooks where, it would appear
> to me, there is no issue.  essentially, i see no reason you could not
> interface an application using hooks and keep that application
> propiertory.

If I'm the original author being referred to, it's important to  
remember that I'm summarizing the position articulated to me by the  
FSF after three days of communication, including detailed  
descriptions of how Drupal's hook system operates and how dynamic  
script languages like PHP handle bridging projects.

Please read earlier messages. The FSF's position is that, if two  
projects are calling each others' functions or sharing in-memory data  
structures and so on (even if they do it via an intermediary plugin),  
they are operating as a single unit. There is a LOT of technical  
wrangling in the details of that, but it comes back to the rule of  
thumb:

*** If you can, at any point, call debug_backtrace() and see BOTH  
drupal functions AND functions from a non-GPL-compatible piece of  
software, the terms of the GPL are being violated. ***

I say this not because I am a torch-waving opponent of proprietary  
software, nor because I am a critic of the GPL. I just think that  
there is a great deal of confusion in the OSS CMS community, and I  
hope to help achieve some clarity. If you have an issue, or a point  
you feel needs to be clarified, ** DO WHAT I DID. CONTACT THE FREE  
SOFTWARE FOUNDATION. ** They're great folks to talk to, and even if  
you don't like the results of your questions, they're very patient  
and willing to help work through the thorny technical details.

--Jeff