From: Jeff King <email@example.com> To: Junio C Hamano <firstname.lastname@example.org> Cc: "Johannes Schindelin via GitGitGadget" <email@example.com>, firstname.lastname@example.org, "Johannes Schindelin" <email@example.com>, 마누엘 <firstname.lastname@example.org> Subject: Re: [PATCH] clean: explicitly `fflush` stdout Date: Wed, 8 Apr 2020 18:38:21 -0400 [thread overview] Message-ID: <20200408223821.GD3468797@coredump.intra.peff.net> (raw) In-Reply-To: <email@example.com> On Wed, Apr 08, 2020 at 02:51:11PM -0700, Junio C Hamano wrote: > > Agreed. I guess it didn't affect people on other platforms much because > > stdout to a terminal is generally line-buffered on POSIX systems. But > > it's better not to rely on that, plus it could create confusion if > > somebody tried to manipulate the interactive operation through a pipe > > (e.g., driving it from a GUI or something). > > Hmph, I thought it was more common to do prompts etc. on the > standard error stream, which tends to make the buffering of the > output less of a problem, but apparently these prompts are given to > the standard output. The prompts in git-add--interactive.perl go to stdout, as do the ones for "am --interactive". I think that's reasonable, if you think of it as the main output of the program. At one point the "am" ones actually went to /dev/tty, but IMHO that's a mistake. In 99% of cases it behaves the same as looking at stdin/stdout (because they're connected to the terminal anyway), and in the other 1% it's just as likely to be the wrong thing as the right. Plus it makes testing much harder. > I am also OK to sprinkle fflush(stdout) but in > the longer term, it would probably be a good idea to introduce a > helper to "prompt then grab input" or "read user input" (if the > former, we'd be able to bring consistency into "which between the > standard output or the standard error does a prompt come?", and if > the latter we'd do fflush(NULL) before reading), especially if there > are many git subcommands that go interactive. Agreed. There is git_prompt(), but that does the tty thing, which I think we'd want to avoid in most cases. It's used by the credential code, which really does want to use a terminal to do things like turn off character echoing. Plus it's not the main function of the program, but rather a side effect (so we have to avoid disrupting the main stdin/stdout). -Peff
next prev parent reply other threads:[~2020-04-08 22:38 UTC|newest] Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top 2020-04-08 19:33 Johannes Schindelin via GitGitGadget 2020-04-08 20:14 ` Jeff King 2020-04-08 21:51 ` Junio C Hamano 2020-04-08 22:38 ` Jeff King [this message] 2020-04-10 14:03 ` Johannes Schindelin 2020-04-10 11:27 ` [PATCH v2 0/2] Explicitly fflush stdout in git clean Johannes Schindelin via GitGitGadget 2020-04-10 11:27 ` [PATCH v2 1/2] Refactor code asking the user for input interactively Johannes Schindelin via GitGitGadget 2020-04-10 12:27 ` Derrick Stolee 2020-04-10 14:01 ` Johannes Schindelin 2020-04-10 15:07 ` Jeff King 2020-04-10 17:44 ` Junio C Hamano 2020-04-10 11:27 ` [PATCH v2 2/2] Explicitly `fflush` stdout before expecting interactive input 마누엘 via GitGitGadget 2020-04-10 12:28 ` Derrick Stolee 2020-04-10 18:16 ` [PATCH v3 0/2] Explicitly fflush stdout in git clean Johannes Schindelin via GitGitGadget 2020-04-10 18:16 ` [PATCH v3 1/2] Refactor code asking the user for input interactively Johannes Schindelin via GitGitGadget 2020-04-10 18:16 ` [PATCH v3 2/2] Explicitly `fflush` stdout before expecting interactive input 마누엘 via GitGitGadget
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