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How does a licence impacts the distribution of plugins? E.g. if I write a plugin for a system (e.g. Wordpress) and I sell this plugin? Does the plugin code ne

by pan69 15y ago

How does a licence impacts the distribution of plugins? E.g. if I write a plugin for a system (e.g. Wordpress) and I sell this plugin? Does the plugin code needs to be distributed under the same licence as the original system even though it wouldn't distribute any of the code provided by the original system? It would only call functions or inherit from classes described in the original system.

handzhiev 15y ago
There's a lot of debate on this topic. Most people agree that plugins should also be GPL, so most are (even the commercial ones)
- raphman 15y ago
  Nice overview of the 2010 Thesis theme debate: http://www.metafilter.com/93802/WordPress-Thesis-and-the-GPL http://www.metafilter.com/93802/WordPress-Thesis-and-the-GPL
tzs 15y ago
There is case law that says that calling functions from something else does not make your code a derivative work of that something else. This issue arose when people started making unauthorized third party games for video game consoles that made use of code in the ROMs of those consoles. The SFLC says that calling a function does make your code a derivative work of that function's code. I've never seen any analysis from them that explains why they think the video game cases don't apply. They are a free software advocacy organization--they naturally tend to take the most free software friendly interpretation possible of law, and I think that often takes them a little past what the law actually is into what they wish it was. It would be interesting for someone to write a simple blogging system with a plugin interface that is compatible with Wordpress' plugin interface, and put it in the public domain. Then anyone making a plugin could claim that they actually wrote it for the public domain system, and that is what they are a derivative work of rather than Wordpress. It would be amusing to see what the SFLC would make of that. Something like this actually happened once, in the early '90s. Someone was distributing a secure email system that used RSA. It used RSA via the RSAREF library, which was freely distributable but not free software. The email system was distributed in source form. When you compiled it, you could compile it to use either the BSD arbitrary precision math library or GMP. Basically, the source had #if statements that selected whether it should assume the BSD library or GMP. (I believe GMP was under GPL, not LGPL, at the time). Stallman didn't like this. The author of the email system then wrote a toy arbitrary precision library that had the same interface as GMP, and that satisfied Stallman.
jakejake 15y ago
Your code can be GPL and you can sell it, the only problem is that you can't prevent other people from selling it as well (or giving it away for free). Also you don't have to provide a free download to the general public. It's just that everyone to whom you distribute your code has the right to request the source code. You don't have to provide source code to people to whom you did not distribute the software. Of course anybody that you did distribute the software is free to put the source code up for public download. There are sites that do that type of thing, I've had GPL software I've written show up on download sites and such. But if you are maintaining your software then they will often be out of date and hopefully you'll be showing up ahead of those in search engine listings for your own products. Basically if you're providing good value, you're less likely to be affected by that type of thing.

by pan69 15y ago

handzhiev 15y ago

There's a lot of debate on this topic. Most people agree that plugins should also be GPL, so most are (even the commercial ones)

raphman 15y ago
Nice overview of the 2010 Thesis theme debate: http://www.metafilter.com/93802/WordPress-Thesis-and-the-GPL http://www.metafilter.com/93802/WordPress-Thesis-and-the-GPL

tzs 15y ago

There is case law that says that calling functions from something else does not make your code a derivative work of that something else. This issue arose when people started making unauthorized third party games for video game consoles that made use of code in the ROMs of those consoles. The SFLC says that calling a function does make your code a derivative work of that function's code. I've never seen any analysis from them that explains why they think the video game cases don't apply. They are a free software advocacy organization--they naturally tend to take the most free software friendly interpretation possible of law, and I think that often takes them a little past what the law actually is into what they wish it was. It would be interesting for someone to write a simple blogging system with a plugin interface that is compatible with Wordpress' plugin interface, and put it in the public domain. Then anyone making a plugin could claim that they actually wrote it for the public domain system, and that is what they are a derivative work of rather than Wordpress. It would be amusing to see what the SFLC would make of that. Something like this actually happened once, in the early '90s. Someone was distributing a secure email system that used RSA. It used RSA via the RSAREF library, which was freely distributable but not free software. The email system was distributed in source form. When you compiled it, you could compile it to use either the BSD arbitrary precision math library or GMP. Basically, the source had #if statements that selected whether it should assume the BSD library or GMP. (I believe GMP was under GPL, not LGPL, at the time). Stallman didn't like this. The author of the email system then wrote a toy arbitrary precision library that had the same interface as GMP, and that satisfied Stallman.

jakejake 15y ago

Your code can be GPL and you can sell it, the only problem is that you can't prevent other people from selling it as well (or giving it away for free). Also you don't have to provide a free download to the general public. It's just that everyone to whom you distribute your code has the right to request the source code. You don't have to provide source code to people to whom you did not distribute the software. Of course anybody that you did distribute the software is free to put the source code up for public download. There are sites that do that type of thing, I've had GPL software I've written show up on download sites and such. But if you are maintaining your software then they will often be out of date and hopefully you'll be showing up ahead of those in search engine listings for your own products. Basically if you're providing good value, you're less likely to be affected by that type of thing.