[DISCUSS] Make TinkerGraph Extendable

[Stephen Mallette <sp...@gmail.com>]

Should TinkerGraph be extendable? This is not a new discussion. Most
notably, Michael Pollmeier long ago wanted to allow for this to
experiment with a TinkerGraph fork where he used schemas to drastically
increase the performance:

https://github.com/ShiftLeftSecurity/tinkergraph-gremlin

which then was replaced by the quite neat:

https://github.com/ShiftLeftSecurity/overflowdb

To the best of my knowledge, the argument against making TinkerGraph
extendable has been that allowing extension of TinkerGraph would create
situations where we felt we couldn't alter TinkerGraph APIs and behaviors
as easily as we would like and wanted to maintain the flexibility to change
what we wanted when we wanted without fear of breaking those extending it.

Since those early discussions to come to that reasoning many years ago,
I've learned that TinkerGraph has a lot of interesting usages that you
normally wouldn't think of. I've seen/heard it used internally within graph
systems quite regularly. This might be for testing or functional purposes
and there are times when being able to extend it would be quite handy where
a fork of TinkerGraph would be too heavy handed. I've also come to the
realization that in our current times, TinkerGraph is quite stable in terms
of API and behavior (the two things we've wanted to protect with "final"
modifiers). There are few changes, the last major one probably relates to
the introduction of null support in 3.5.0 almost 12 months ago.

Given these realizations and another recent request to "remove a final" in
TinkerGraph, I've started to wonder if the reasons we had many years ago
still hold and am inclined to think that they do not. Does anyone have
thoughts on the matter?

As an aside, it's interesting that when a project lives long enough, the
decisions that felt like absolutes begin to feel a bit more mutable. For
example, for years we thought we'd never maintain Gremlin in other
languages in our repository, but now we hold many languages here and GLVs
are highly popular in what they allow. Sorta thought provoking....