From: Jonathan Nieder <jrnieder@gmail.com>
To: Emily Shaffer <emilyshaffer@google.com>
Cc: Jeff King <peff@peff.net>, git@vger.kernel.org
Subject: Re: [PATCH v2] grep: provide sane default to grep_source struct
Date: Tue, 21 May 2019 17:17:36 -0700 [thread overview]
Message-ID: <20190522001736.GA219159@google.com> (raw)
In-Reply-To: <20190521235212.GA46998@google.com>
Hi,
Emily Shaffer wrote:
> On Thu, May 16, 2019 at 06:02:54PM -0400, Jeff King wrote:
>> On Thu, May 16, 2019 at 02:44:44PM -0700, Emily Shaffer wrote:
>>> + /* TODO: In the future it may become desirable to pass in the name as
>>> + * an argument to grep_buffer(). At that time, "(in core)" should be
>>> + * replaced.
>>> + */
(micronit, likely moot: Git's multi-line comments start with "/*" on
its own line:
/*
* NEEDSWORK: Passing the name in as an argument would allow
* "(in core)" to be replaced.
*/
.)
>>> + grep_source_init(&gs, GREP_SOURCE_BUF, _("(in core)"), NULL, NULL);
>>
>> Hmm. I don't see much point in this one, as it would just avoid
>> triggering our BUG(). If somebody is adding new grep_buffer() callers
>> that don't use status_only, wouldn't we want them to see the BUG() to
>> know that they need to refactor grep_buffer() to provide a name?
[...]
> Can we think of a reason anybody would want to be able to use it this
> way with the placeholder string?
I agree with Peff here: using NULL puts this in a better place with
respect to Rusty's API design manifesto[1].
With the "(in core)" default, I may end up triggering the "(in core)"
behavior in production, because there is not a clear enough signal
that my code path is making a mistake. That's problematic because it
gives the end user a confusing experience: the end user cares where
the line comes from, not that it spent a second or two in core.
With the NULL default, *especially* after this patch, such usage would
instead trigger a BUG: line in output, meaning
- if it gets exercised in tests, the test will fail, prompting the
patch auther to pass in a more appropriate label
- if it gets missed in tests and gets triggered in production, the error
message makes it clear that this is a mistake so the user is likely
to report a bug instead of assuming this is deliberate but confusing
behavior
In that vein, this patch is very helpful, since the BUG would trip
*consistently*, not only when the grep pattern matches. Failing
consistently like this is a huge improvement in API usability.
It would be even better if we could catch the problem at compile time,
but one thing at a time.
Thanks,
Jonathan
[1] https://ozlabs.org/~rusty/index.cgi/tech/2008-03-30.html,
https://ozlabs.org/~rusty/index.cgi/tech/2008-04-01.html
next prev parent reply other threads:[~2019-05-22 0:17 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-05-16 2:00 [RFC PATCH] grep: provide sane default to grep_source struct Emily Shaffer
2019-05-16 3:07 ` Junio C Hamano
2019-05-16 3:13 ` Jonathan Nieder
2019-05-16 3:11 ` Jonathan Nieder
2019-05-16 21:05 ` Emily Shaffer
2019-05-16 21:44 ` [PATCH v2] " Emily Shaffer
2019-05-16 22:02 ` Jeff King
2019-05-21 23:52 ` Emily Shaffer
2019-05-22 0:17 ` Jonathan Nieder [this message]
2019-05-22 0:34 ` [PATCH v3] " Emily Shaffer
2019-05-22 0:58 ` Jonathan Nieder
2019-05-22 4:01 ` Jeff King
2019-05-23 20:23 ` [PATCH v4] grep: fail if call could output and name is null Emily Shaffer
2019-05-23 20:34 ` Jonathan Nieder
2019-05-28 17:57 ` Junio C Hamano
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
List information: http://vger.kernel.org/majordomo-info.html
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20190522001736.GA219159@google.com \
--to=jrnieder@gmail.com \
--cc=emilyshaffer@google.com \
--cc=git@vger.kernel.org \
--cc=peff@peff.net \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
Code repositories for project(s) associated with this public inbox
https://80x24.org/mirrors/git.git
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for read-only IMAP folder(s) and NNTP newsgroup(s).