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From: Junio C Hamano <gitster@pobox•com>
To: Karthik Nayak <karthik.188@gmail•com>
Cc: Git <git@vger•kernel.org>,
	Christian Couder <christian.couder@gmail•com>,
	Matthieu Moy <Matthieu.Moy@grenoble-inp•fr>
Subject: Re: [PATCH v15 05/13] ref-filter: implement an `align` atom
Date: Wed, 02 Sep 2015 08:45:59 -0700	[thread overview]
Message-ID: <xmqqy4goomdk.fsf@gitster.mtv.corp.google.com> (raw)
In-Reply-To: <CAOLa=ZQLG_HB0trodXPCb9n4x2FuH7h7-+KJYLEdNZSpd0PHsg@mail.gmail.com> (Karthik Nayak's message of "Wed, 2 Sep 2015 20:35:11 +0530")

Karthik Nayak <karthik.188@gmail•com> writes:

> On Wed, Sep 2, 2015 at 8:31 PM, Junio C Hamano <gitster@pobox•com> wrote:
>> Karthik Nayak <karthik.188@gmail•com> writes:
>>
>>>>> +             die(_("format: `end` atom used without a supporting atom"));
>>>>
>>>> Not a show-stopper, but we may need some wordsmithing for "a
>>>> supporting atom" here; an end-user would not know what it is.
>>>
>>> Probably something like "format: `end` atom should only be
>>> used with modifier atoms".
>>
>> Between "supporting" and "modifier" I do not see much difference,
>> though.
>
> I don't see how we could provide a better message, as %(end) atom
> would be common to various atoms eventually.

I said "not a show-stopper" without giving a suggestion exactly
because I didn't (and I still don't) think either you or I can come
up with a good wording ;-).  That is why the message was Cc'ed to
the list for others to comment.

>>> Cause we wanted to provide an error for usage of "%(ailgn)" without any
>>> subvalues as such.
>>
>> Wouldn't it be something that would be caught in the same codepath
>> as what catches %(unrecognized) in the format string?

One potential issue you have with prefix matching with "align" is
that you can never have a different atom whose name happens to begin
with that substring.  I think the best behaviour is for the higher
level parser to recognize %(ATOM) and %(ATOM:anything) and nothing
else for all ATOM in the valid atoms registry.  That would prevent
%(ATOMfoo) from being handled as part of handling ATOM.

And make the code consider %(ATOM) form as a short-hand for %(ATOM:)
that does not have customizations.  Conceptually %(refname) is a
%(refname:default).

For an atom like 'align' that does not have a reasonable default,
the parser for 'align' can notice that a required customization is
missing and give an error that is specific to 'align'.

So all calls in your code of the from

	... else if (skip_prefix(name, "align", &val)) {
        	...

should become a call to helper that does more than skip_prefix().

int match_atom_name(const char *name, const char *atom_name, char **val)
{
	char *body

       	if (!skip_prefix(name, atom_name, &body))
        	return 0; /* doesn't even begin with "align" */
	if (!body[0]) {
        	*val = NULL; /* %(align) and no customization */
                return 1;
	}
	if (body[0] != ':')
        	return 0; /* "alignfoo" is not "align" or "align:..." */
	*val = body + 1; /* "align:val" */
        return 1;
}

  reply	other threads:[~2015-09-02 15:46 UTC|newest]

Thread overview: 58+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2015-09-01 18:26 [PATCH v15 00/13] port builtin/tag.c to use ref-filter APIs Karthik Nayak
2015-09-01 18:26 ` [PATCH v15 01/13] ref-filter: move `struct atom_value` to ref-filter.c Karthik Nayak
2015-09-01 18:26 ` [PATCH v15 02/13] ref-filter: introduce ref_formatting_state and ref_formatting_stack Karthik Nayak
2015-09-01 18:26 ` [PATCH v15 03/13] utf8: add function to align a string into given strbuf Karthik Nayak
2015-09-01 18:26 ` [PATCH v15 04/13] ref-filter: introduce handler function for each atom Karthik Nayak
2015-09-01 18:26 ` [PATCH v15 05/13] ref-filter: implement an `align` atom Karthik Nayak
2015-09-01 21:19   ` Junio C Hamano
2015-09-02 11:51     ` Karthik Nayak
2015-09-02 15:01       ` Junio C Hamano
2015-09-02 15:05         ` Karthik Nayak
2015-09-02 15:45           ` Junio C Hamano [this message]
2015-09-02 16:09             ` Karthik Nayak
2015-09-02 17:10             ` Matthieu Moy
2015-09-02 17:28               ` Junio C Hamano
2015-09-03 13:30                 ` Karthik Nayak
2015-09-02 15:50         ` Matthieu Moy
2015-09-02  8:41   ` Matthieu Moy
2015-09-02 12:51     ` Karthik Nayak
2015-09-02  8:45   ` Matthieu Moy
2015-09-02 13:12     ` Karthik Nayak
2015-09-02 15:50       ` Matthieu Moy
2015-09-03 14:12   ` Eric Sunshine
2015-09-03 16:01     ` Karthik Nayak
2015-09-03 16:23     ` Junio C Hamano
2015-09-04 18:02       ` Karthik Nayak
2015-09-01 18:26 ` [PATCH v15 06/13] ref-filter: add option to filter out tags, branches and remotes Karthik Nayak
2015-09-01 21:30   ` Junio C Hamano
2015-09-02  1:27     ` Karthik Nayak
2015-09-02  4:15       ` Junio C Hamano
2015-09-02 12:48         ` Karthik Nayak
2015-09-01 18:26 ` [PATCH v15 07/13] ref-filter: add support for %(contents:lines=X) Karthik Nayak
2015-09-02  9:07   ` Matthieu Moy
2015-09-02 14:16     ` Karthik Nayak
2015-09-02 16:11       ` Matthieu Moy
2015-09-03 13:34         ` Karthik Nayak
2015-09-03 13:49           ` Karthik Nayak
2015-09-03 14:47             ` Matthieu Moy
2015-09-03 16:05               ` Karthik Nayak
2015-09-03 14:39   ` Eric Sunshine
2015-09-03 14:47     ` Eric Sunshine
2015-09-03 15:05       ` Matthieu Moy
2015-09-03 16:04         ` Karthik Nayak
2015-09-03 16:27       ` Junio C Hamano
2015-09-04 12:35         ` Karthik Nayak
2015-09-03 15:01     ` Matthieu Moy
2015-09-03 16:03     ` Karthik Nayak
2015-09-01 18:26 ` [PATCH v15 08/13] ref-filter: add support to sort by version Karthik Nayak
2015-09-01 18:26 ` [PATCH v15 09/13] ref-filter: add option to match literal pattern Karthik Nayak
2015-09-01 18:26 ` [PATCH v15 10/13] tag.c: use 'ref-filter' data structures Karthik Nayak
2015-09-01 18:26 ` [PATCH v15 11/13] tag.c: use 'ref-filter' APIs Karthik Nayak
2015-09-02  9:09   ` Matthieu Moy
2015-09-02 15:10   ` Junio C Hamano
2015-09-02 15:40     ` Karthik Nayak
2015-09-02 16:13       ` Matthieu Moy
2015-09-02 16:43         ` Junio C Hamano
2015-09-03 13:32           ` Karthik Nayak
2015-09-01 18:26 ` [PATCH v15 12/13] tag.c: implement '--format' option Karthik Nayak
2015-09-01 18:26 ` [PATCH v15 13/13] tag.c: implement '--merged' and '--no-merged' options Karthik Nayak

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