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From: Junio C Hamano <gitster@pobox.com>
To: Stefan Beller <sbeller@google.com>
Cc: git@vger.kernel.org
Subject: Re: [PATCH 03/11] sha1-array: provide oid_array_filter
Date: Thu, 06 Sep 2018 10:20:30 -0700	[thread overview]
Message-ID: <xmqqsh2m1r1d.fsf@gitster-ct.c.googlers.com> (raw)
In-Reply-To: <20180904230149.180332-4-sbeller@google.com> (Stefan Beller's message of "Tue, 4 Sep 2018 16:01:41 -0700")

Stefan Beller <sbeller@google.com> writes:

> +/* Call fn for each oid, and retain it if fn returns 0, remove it otherwise */
> +int oid_array_filter(struct oid_array *array,
> +		     for_each_oid_fn fn,
> +		     void *cbdata);

Comparing this with object_array_filter(), which I think this was
modeled after, I notice that this is much harder to remember how to
use it correctly.

    void object_array_filter(struct object_array *array,
                             object_array_each_func_t want, void *cb_data)

It is clear to a potential user of this function who needs to
implement the callback function what the function should return,
because it calls it "want" (as opposed to "fn").  The function must
answer "I want to keep this?  Yes/no?".

Also polarity of oid_array_filter()'s callback is different.  It
retains elements for which "fn" returns false.

So one step of improvement may be to rename "fn" to "reject", but as
we do not have any caller of this new function yet, perhaps match
the polarity and call it "want"?

I think "x_filter" is perhaps trying to match other language's
filter(), e.g. Python's

	>>> filter(lambda x: x % 2 == 0, range(0,10))
	[0, 2, 4, 6, 8]

so "say yes if you want to keep it" may be more familiar than "say
yes if you want to filter it out".


  reply	other threads:[~2018-09-06 17:20 UTC|newest]

Thread overview: 39+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-09-04 23:01 [PATCH 00/11] fetch: make sure submodule oids are fetched Stefan Beller
2018-09-04 23:01 ` [PATCH 01/11] string_list: print_string_list to use trace_printf Stefan Beller
2018-09-06 16:52   ` Junio C Hamano
2018-09-06 16:56     ` Jeff King
2018-09-06 22:16       ` Stefan Beller
2018-09-07  0:04         ` Jeff King
2018-09-07  9:53           ` Junio C Hamano
2018-09-07 17:21             ` Stefan Beller
2018-09-10 21:58               ` [PATCH 1/2] trace: add trace_print_string_list_key Stefan Beller
2018-09-10 21:58                 ` [PATCH 2/2] string-list: remove unused function print_string_list Stefan Beller
2018-09-10 22:32                 ` [PATCH 1/2] trace: add trace_print_string_list_key Junio C Hamano
2018-09-10 22:38                   ` Stefan Beller
2018-09-11  0:52                     ` Junio C Hamano
2018-09-11  3:08                       ` Stefan Beller
2018-09-11 21:03                         ` Jeff King
2018-09-11 18:48                       ` [PATCH] string-list: remove unused function print_string_list Stefan Beller
2018-09-11 19:27                         ` Junio C Hamano
2018-09-11 19:30                           ` Junio C Hamano
2018-09-11 19:47                             ` Stefan Beller
2018-09-11 20:53                               ` Junio C Hamano
2018-09-04 23:01 ` [PATCH 02/11] string-list.h: add string_list_{pop, last} functions Stefan Beller
2018-09-06 17:10   ` Junio C Hamano
2018-09-06 22:29     ` Stefan Beller
2018-09-04 23:01 ` [PATCH 03/11] sha1-array: provide oid_array_filter Stefan Beller
2018-09-06 17:20   ` Junio C Hamano [this message]
2018-09-04 23:01 ` [PATCH 04/11] submodule.c: convert submodule_move_head new argument to object id Stefan Beller
2018-09-06 17:31   ` Junio C Hamano
2018-09-04 23:01 ` [PATCH 05/11] submodule.c: fix indentation Stefan Beller
2018-09-06 17:34   ` Junio C Hamano
2018-09-04 23:01 ` [PATCH 06/11] submodule.c: sort changed_submodule_names before searching it Stefan Beller
2018-09-06 18:03   ` Junio C Hamano
2018-09-11 18:31     ` Stefan Beller
2018-09-04 23:01 ` [PATCH 07/11] submodule: move global changed_submodule_names into fetch submodule struct Stefan Beller
2018-09-06 18:04   ` Junio C Hamano
2018-09-04 23:01 ` [PATCH 08/11] submodule.c: do not copy around submodule list Stefan Beller
2018-09-06 18:20   ` Junio C Hamano
2018-09-04 23:01 ` [PATCH 09/11] submodule: fetch in submodules git directory instead of in worktree Stefan Beller
2018-09-04 23:01 ` [PATCH 10/11] fetch: retry fetching submodules if sha1 were not fetched Stefan Beller
2018-09-04 23:01 ` [PATCH 11/11] builtin/fetch: check for submodule updates for non branch fetches Stefan Beller

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