From: Jeff King <peff@peff.net>
To: Junio C Hamano <gitster@pobox.com>
Cc: "René Scharfe" <l.s.r@web.de>, "Git List" <git@vger.kernel.org>,
"Chandra Pratap" <chandrapratap3519@gmail.com>
Subject: Re: [RFC][PATCH] t-prio-queue: simplify using compound literals
Date: Sat, 6 Apr 2024 21:28:44 -0400 [thread overview]
Message-ID: <20240407012844.GC1085004@coredump.intra.peff.net> (raw)
In-Reply-To: <xmqqedbjtqnr.fsf@gitster.g>
On Fri, Apr 05, 2024 at 03:01:44PM -0700, Junio C Hamano wrote:
> Jeff King <peff@peff.net> writes:
>
> > Yeah, this seems pretty reasonable. I think we've traditionally been
> > hesitant to pass or return structs by value, but that's mostly
> > superstition.
>
> We should still be hesitant against the practice to the same degree
> that we are hesitant against struct assignment, especially when the
> struct is of nontrivial size, or the struct has a pointer member
> whose memory ownership semantics goes against shallow copying of the
> struct.
Good point. There are really two thresholds: is this something that
should be totally forbidden, and is this something that is generally a
good idea. I think the answers here are "no" and "yes" respectively.
It is an OK solution for "plain old data" types like date_mode that are
essentially just marshalling arguments, but not for more object-oriented
code that might have ownership over pointers.
> In this particular case, I do not know offhand if .strftime_fmt is
> safe to be shallowly copied, but I trust you two know and/or have
> already looked at the implications.
René already went through each caller, but yeah, I think it is fine
here. This whole thing is just a convenience over having callers pass
around a separated (enum, strftime_fmt, local) triple.
-Peff
next prev parent reply other threads:[~2024-04-07 1:28 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-04-02 18:30 [RFC][PATCH] t-prio-queue: simplify using compound literals René Scharfe
2024-04-02 20:31 ` Junio C Hamano
2024-04-02 20:41 ` Jeff King
2024-04-05 17:44 ` René Scharfe
2024-04-05 19:17 ` Jeff King
2024-04-05 22:01 ` Junio C Hamano
2024-04-06 7:06 ` René Scharfe
2024-04-07 1:28 ` Jeff King [this message]
2024-04-08 16:57 ` Junio C Hamano
2024-04-08 17:09 ` Jeff King
2024-04-11 21:23 ` Josh Steadmon
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