Re: [PATCH 0/4] Compile-time extensions for list-object-filter

Good point - sorry I sent this out without accompanying explanation. I'm still learning about contributing to Git.

The filter extension that I want to implement is a spatial filter - it will return blobs that store geometries that intersect with a given geometry, eg, "only return blobs in North America". This is useful to us at kartproject.org, "distributed version control for geospatial data", which is built on Git. But safe to say that this functionality is not generally useful to Git users.

However, the idea we have is that there will be others who want to implement custom filters also - perhaps like the spatial filter, these could be domain-specific filters that are not useful to most Git users, but allow for a custom Git to be more powerful when storing data from a particular domain. We could just fork git and do what we want with the fork, but defining a plugin interface makes it possible for us to keep using Git at master, instead of maintaining a fork indefinitely.

My colleague Robert Coup coded this up once already as a plugin library interface that could be loaded at runtime, and I've been tasked with rewriting it as a compile-time interface, which he thought was "more likely" (but of course not guaranteed) to be accepted as a worthwhile change to Git. He's unfortunately on the other side of the world to me and not working today, but I hope when he reappears he'll be able to say something more in defence of this idea, and perhaps give a history of the reasoning for this particular solution.

Regarding licenses: the sample extensions I'm contributing will be covered by Git's GPL-v2 (I assume), if they make it into the Git repository. Any other extensions that may be written by third party authors and are maintained elsewhere could be licensed as those authors see fit, as long as they take care not to violate the terms of Git's GPL-v2 when they distribute the extension or Git and the extension together. I could add a link to the GPL-v2 in the README warning developers to check it before distributing any kind of extension to Git. I'm not a lawyer and wouldn't want to give more specific advice than that.

On Tue, Sep 7, 2021 at 11:24 AM Bagas Sanjaya <bagasdotme@gmail.com> wrote: