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

[Pierre-Yves David]

On 09/25/2016 12:43 AM, Matt Mackall wrote:
> On Sat, 2016-09-24 at 00:22 +0200, Pierre-Yves David wrote:
>>
>> 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)'
>
> You get to implement this version, because I think it's an awful idea.

hu? I'm not sure of when the Mercurial review process switched to from 
"reviewers give feedback to submitter" to "reviewer can update submitter 
patch them-self if they don't like it". That seems quite the opposite of 
what you have been teaching us in the past 10 years.

The changes currently discussed is not a full rewrite of the series. It 
is a minor change in the way the feature is surface to the user (for 
both revset and template).

Of course the discussion is just starting and still open. But so far, 
three major contributors have voiced their preference for foozy idea. 
I'm looking forward to read your argument about why the idea is awful.

Cheers,

-- 
Pierre-Yves David