Hey All,

Matt - just to maybe clarify by examples...are you thinking things like Trident or powderday are sorts of yt extensions that you mean?  (If so, then I do like this idea a lot too).  I think one might imagine having a clear set of guidelines for developers of extensions to aspire toward (even if it's for example, having some basic set of or style of documentation) so that from the user point, when looking at extensions  on the yt docs, there's some modicum of uniformity.  That might make it easier for users to browse and understand the extensions.

-d

On Mon, Jan 18, 2016 at 12:43 PM, Matthew Turk <matthewturk@gmail.com> wrote:
On Mon, Jan 18, 2016 at 11:32 AM, John ZuHone <jzuhone@gmail.com> wrote:
> Matt can correct me if I am wrong, but I was under the impression that the two components of the proposal were separate and not inevitably tied to one another.
>
> I am in strong support of the idea of extensions, but I strongly disagree with most of the second component of this proposal. I believe it is far too disruptive, and I honestly don’t see the argument for it (except maybe splitting some astro-specific stuff out into an extension). But spinning off stuff like volume rendering and other big components like that seems unnecessary.
>

No need to correct; the second one is indeed an extension of the
first, and a separate proposal.

>> On Jan 18, 2016, at 12:26 PM, Matthew Turk <matthewturk@gmail.com> wrote:
>>
>> Hi Nathan,
>>
>> Just to quickly address one component before anybody else replies: I
>> would volunteer to do the majority of this work (which I think from a
>> technical perspective is not necessarily too bad), and I don't see it
>> being a 3.X release, but maybe a 4.0 release, and I don't have answers
>> for when it would happen since I think that is a community decision we
>> shouldn't rush into.
>>
>> On Mon, Jan 18, 2016 at 11:21 AM, Nathan Goldbaum <nathan12343@gmail.com> wrote:
>>> Just a few thoughts about this.
>>>
>>> I think encouraging more external packages to depend on yt will be great,
>>> and will keep us more honest about the backward compatibility guarantees
>>> we've committed ourselves to. Building social capital by encouraging an
>>> "affiliated" package ecosystem like astropy has is also good, both for
>>> social capital and also by enabling cool new features for our users.
>>>
>>> That said, I'm skeptical about some of the technical components of Matt's
>>> proposal. In particular, I'm concerned with the amount of work required to
>>> make major changes to the core yt codebase, while still maintaining backward
>>> compatibility. Who will do this work? When will it happen? Would this
>>> constitute a yt 4.0 release?
>>>
>>> While I do think making the core yt package less astronomy focused is good,
>>> I also think it's possible to do so while maintaining strong backward
>>> compatibility guarantees, or at least going through a deprecation cycle over
>>> the course of several minor versions. I don't think making another cycle of
>>> breaking changes so soon after yt-3.0 is a good idea, as that will impose a
>>> large amount of work both on the yt developers and on our users.
>>>
>>> On Mon, Jan 18, 2016 at 9:43 AM, Matthew Turk <matthewturk@gmail.com> wrote:
>>>>
>>>> Hi everyone,
>>>>
>>>> The last couple weeks I’ve been thinking a lot about the future of yt.
>>>> What I’d like to propose is that we shift investment in yt as a
>>>> single, monolithic codebase into yt as a project, or an ecosystem of
>>>> projects.
>>>>
>>>> This came out of the discussion of the extension/affiliated packages,
>>>> analysis modules, and so on.  Britton has for a while been pitching
>>>> the idea [which I will poorly paraphrase here] that yt can be the
>>>> framework on top of which killer apps can be built.  I think this is
>>>> great.
>>>>
>>>> What’s holding us back in some ways from this is that yt is currently
>>>> structured as a monolithic code base, with little to no discovery of
>>>> other packages and apps and whatnot.  We tried for a while to change
>>>> this with The Barn, but it ended up not quite taking off.  I think the
>>>> time is right to try to change the way we think about yt to be more
>>>> about yt the Project, rather than yt the Codebase; the core codebase
>>>> is an important component of this, but not the whole of it.
>>>>
>>>> Encouraging an ecosystem of packages can have a few very important
>>>> benefits:
>>>>
>>>> * External packages will confer greater individual credit to the
>>>> folks who develop them.
>>>> * External packages can be versioned and developed independently; the
>>>> review process can be different.
>>>> * yt’s core can be emphasized as a generic package, on top of which
>>>> astronomy analysis can be built.
>>>> * Packages can be maintained wherever, including alternate locations
>>>> such as github.
>>>>
>>>> On the other hand, having packages inside the main distribution makes
>>>> discoverability much, much easier.  It also enables everything to be
>>>> In The Box.  And, the continuous integration and testing system is
>>>> already set up for yt.  But, these are all possible to overcome -- we
>>>> can devise a strategy for adding packages to the CI system (and if
>>>> they are externally managed, they can also rely on yt as a dependency
>>>> and use whatever CI system they like!) and we can improve
>>>> discoverability by refocusing the website to enable this.  I've asked
>>>> Kacper about adding new packages, and it's not as easy as it might
>>>> seem, so we may need to be careful about how that process occurs; one
>>>> possibility would be to provide servers and ready-made setups, but
>>>> have individuals do the heavy lifting.  We could even have something
>>>> in the codebase that describes some packages that are available.
>>>> External packages could have much looser dependency rules, which means
>>>> they can be free to take advantage of things like OpenCL, numba, etc,
>>>> without having to add them to the primary codebase.
>>>>
>>>> Synchronizing APIs and versions across extension packages may be
>>>> difficult in some particular cases, but I suspect in practice will not
>>>> be an issue, as long as we continue to have a reasonably stable
>>>> *public* API, and graduate a few things (such as .blocks) into a
>>>> public API from semi-private.
>>>>
>>>> To this end, of really encouraging an ecosystem of packages, I’d like
>>>> to propose two things, in increasing order of disruptiveness.
>>>>
>>>> First: Encourage extension packages.  This would mean:
>>>> * Reorganize website to allow for extension packages to be displayed
>>>> prominently
>>>> * Add support for name-space packages in yt
>>>> * (possible) split out some packages from analysis_modules, including
>>>> halo finding
>>>> * Codify process of extension package creation, including how to have
>>>> CI set up for them and build system.
>>>>
>>>> The second, more disruptive proposal:
>>>> * Split yt into subprojects.  This would include spinning out the
>>>> volume rendering and some or all of the frontends, and probably the
>>>> testing infrastructure as well.
>>>> * Split further astro-specific routines into an astro extension, and
>>>> begin the process of doing this with other domains as well.  (As in
>>>> the long-simmering domain context YTEP.)
>>>>
>>>> I’ll invite comments from everyone, but particularly from folks who
>>>> have either not contributed to an analysis module or extension package
>>>> because of concerns that would be addressed by this, as well as from
>>>> core developers this would impact.  If the thread gets too unweildy we
>>>> may also want to table this for the next yt team meeting.
>>>>
>>>> Thanks,
>>>>
>>>> Matt
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