From: Junio C Hamano <gitster@pobox•com>
To: Jeff King <peff@peff•net>
Cc: git@vger•kernel.org
Subject: Re: [PATCH 5/8] string-list: add pos to iterator callback
Date: Tue, 01 Jul 2014 10:45:19 -0700 [thread overview]
Message-ID: <xmqq1tu5x9ao.fsf@gitster.dls.corp.google.com> (raw)
In-Reply-To: <20140625234252.GE23146@sigill.intra.peff.net> (Jeff King's message of "Wed, 25 Jun 2014 19:42:52 -0400")
Jeff King <peff@peff•net> writes:
> When we are running a string-list foreach or filter, the
> callback function sees only the string_list_item, along with
> a void* data pointer provided by the caller. This is
> sufficient for most purposes.
>
> However, it can also be useful to know the position of the
> item within the string (for example, if the data pointer
s/the string/&-list/ (or s/&/&_list/).
> points to a secondary array in which each element
> corresponds to part of the string list). We can help this
> use case by providing the position to each callback.
>
> Signed-off-by: Jeff King <peff@peff•net>
> ---
> The diff here is noisy, and I expect in the long run that the one caller
> I add to builtin/tag.c later in the series will eventually stop using
> string_list entirely (in favor of a custom struct), which may leave us
> with no callers that actually use the new field.
>
> I do think the logic above is sound, though, and it's a potentially
> useful thing. There may be other sites that avoid the for_each wrapper
> in favor of iterating themselves simply _because_ they needed to know
> the position (I would just do the same here, except that my new caller
> wants to use filter_string_list, which is a little more complicated).
While I can buy that some callers would want to learn the pos in the
list, I am not sure if this is a good direction to go. Primarily, I
am having trouble sifting between "want" and "need".
How often do callers want to do this? If only narrow specialized
callers want this, is it unreasonable to ask them to add a "int ctr"
in their cb_data and use "pos = ((struct theirs *)cb_data)->ctr++"
in their callback instead?
next prev parent reply other threads:[~2014-07-01 17:45 UTC|newest]
Thread overview: 26+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-06-25 23:34 [PATCH 0/8] use merge-base for tag --contains Jeff King
2014-06-25 23:35 ` [PATCH 1/8] tag: allow --sort with -n Jeff King
2014-06-25 23:35 ` [PATCH 2/8] tag: factor out decision to stream tags Jeff King
2014-06-25 23:39 ` [PATCH 3/8] paint_down_to_common: use prio_queue Jeff King
2014-07-01 16:23 ` Junio C Hamano
2014-07-01 17:10 ` Jeff King
2014-06-25 23:40 ` [PATCH 4/8] add functions for memory-efficient bitmaps Jeff King
2014-06-26 3:15 ` Torsten Bögershausen
2014-06-26 15:51 ` Jeff King
2014-06-29 7:41 ` Eric Sunshine
2014-06-30 17:07 ` Jeff King
2014-07-01 16:57 ` Junio C Hamano
2014-07-01 17:18 ` Jeff King
2014-06-25 23:42 ` [PATCH 5/8] string-list: add pos to iterator callback Jeff King
2014-07-01 17:45 ` Junio C Hamano [this message]
2014-07-01 19:00 ` Jeff King
2014-06-25 23:47 ` [PATCH 6/8] commit: provide a fast multi-tip contains function Jeff King
2014-06-26 18:55 ` Junio C Hamano
2014-06-26 19:19 ` Junio C Hamano
2014-06-26 19:26 ` Junio C Hamano
2014-07-01 18:16 ` Junio C Hamano
2014-07-01 19:14 ` Junio C Hamano
2014-06-25 23:49 ` [PATCH 7/8] tag: use commit_contains Jeff King
2014-06-25 23:53 ` [PATCH 8/8] perf: add tests for tag --contains Jeff King
2014-06-26 0:01 ` Jeff King
2014-06-26 0:04 ` Jeff King
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