[PATCH 2 of 5] extdata: add revset support for extdata

[Pierre-Yves David]

On 09/23/2016 07:34 PM, Matt Mackall wrote:
> On Fri, 2016-09-23 at 19:49 +0900, FUJIWARA Katsunori wrote:
>> At Thu, 22 Sep 2016 13:21:36 -0500,
>> Matt Mackall wrote:
>>>
>>>
>>> # HG changeset patch
>>> # User Matt Mackall <mpm at selenic.com>
>>> # Date 1474293900 18000
>>> #      Mon Sep 19 09:05:00 2016 -0500
>>> # Node ID 9c8847df32a0c5045e60aded2e03a9c97507f909
>>> # Parent  19bf2776dfe39befdc479253e1e7d030b41c08f9
>>> extdata: add revset support for extdata
>>>
>>> This inserts extdata into the revset function support. Planned
>>> extensions of extdata support arguments, so this is the most
>>> appropriate place for it.
>>>
>>> Unfortunately, the registrar framework is not a good fit here. First,
>>> setting an appropriate load point is still an unsolved problem (we
>>> want the code to live in revset.py, but that module may never be loaded).
>>> Second, registered methods become global and the data sources are likely to
>>> be
>>> repo-specific. This won't work well in a context like hgwebdir.
>> Is there any reason not to define extdata() revset predicate (or
>> template function), which requires external data source name like as
>> extdata('filedata') ? (for convenience ?)
>
> It's mostly convenience. But I also plan to add support for arguments.

I think I really like foozy idea about using a generic 'extdata("key")' 
predicate. That will probably be okay for many case and prevent 
unexpected collision with other revsets. If needed, the user can easily 
define a revset alias for the sources in needs easy access to. As 
configuration of the source is needed anyway, this does seems like a 
bearable burden.

If I remember correctly, it does not seems to have limitation in the 
current implementation of revset that would prevent use to do 
'extdata("key", arg1, arg2)'

-- 
Pierre-Yves David