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Re: [PATCH v2] launch_editor(): indicate that Git waits for user input

From
Eric Sunshine <sunshine@sunshineco.com>
Date
Nov 17, 2017, 19:41 UTC
Message-ID
<CAPig+cQ3a0guJUhnbktrjs6fL6mSrUXmPqR0BafEAOhVr7Sy-w@mail.gmail.com>
In-Reply-To
<20171117135109.18071-1-lars.schneider@autodesk.com>
On Fri, Nov 17, 2017 at 8:51 AM,  <lars.schneider@autodesk.com> wrote:
Show 18 quoted lines
> When a graphical GIT_EDITOR is spawned by a Git command that opens
> and waits for user input (e.g. "git rebase -i"), then the editor window
> might be obscured by other windows. The user may be left staring at the
> original Git terminal window without even realizing that s/he needs to
> interact with another window before Git can proceed. To this user Git
> appears hanging.
>
> Show a message in the original terminal and get rid of it when the
> editor returns.
>
> Signed-off-by: Junio C Hamano <gitster@pobox.com>
> Signed-off-by: Lars Schneider <larsxschneider@gmail.com>
> ---
> diff --git a/editor.c b/editor.c
> @@ -40,6 +40,32 @@ int launch_editor(const char *path, struct strbuf *buffer, const char *const *en
> +               static const char *close_notice = NULL;
> +
> +               if (isatty(2) && !close_notice) {

If you reverse this condition to say (!close_notice && isatty(2)), then you save an isatty() invocation each time if close_notice is already assigned.

However, it's not clear how much benefit you gain from stashing this away in a static variable. Premature optimization?

Show 21 quoted lines
> +                       char *term = getenv("TERM");
> +
> +                       if (term && strcmp(term, "dumb"))
> +                               /*
> +                                * go back to the beginning and erase the
> +                                * entire line if the terminal is capable
> +                                * to do so, to avoid wasting the vertical
> +                                * space.
> +                                */
> +                               close_notice = "\r\033[K";
> +                       else
> +                               /* otherwise, complete and waste the line */
> +                               close_notice = "done.\n";
> +               }
> +
> +               if (close_notice) {
> +                       fprintf(
> +                               stderr,
> +                               "Launched your editor ('%s'). Adjust, save, and close the "
> +                               "file to continue. Waiting for your input... ", editor
> +                       );
Here's what this looks like for me:

--- 8< --- Launched your editor ('/Applications/Emacs.app/Contents/MacOS/bin/emacsclient'). Adjust, save, and close the file to continue. Waiting for your input... Waiting for Emacs... --- 8< ---

Very, very noisy, so much so that it's almost unreadable. There are at least three reasons for the noise:

* The raw message itself is already overly long. Do we really need to
assume that newcomers are so clueless that they need it spelled out to
such a level of detail? "Launched editor" should be enough for most
people, and one would hope that "Launched editor; waiting for
input..." would be enough for the rest.
* Does not take into consideration that EDITOR might be very long;
perhaps you could just print the basename and strip arguments (i.e.
"/my/long/path/edit -x --foo --zap" becomes "edit"). Or, just omit the
editor altogether.
* emacsclient already prints its own message ("Waiting for Emacs...",
which runs together with Git's message). Perhaps treat emacsclient as
a special case and skip printing this message if emacsclient is in
use: if (strstr(...,"emacsclient"))

And, of course, with a "dumb" terminal, it's even noisier with the extra "done." at the end:

--- 8< --- Launched your editor ('/Applications/Emacs.app/Contents/MacOS/bin/emacsclient'). Adjust, save, and close the file to continue. Waiting for your input... Waiting for Emacs... done. --- 8< ---

As Junio pointed out in [1], emacsclient has already emitted a newline, so the clear-line sequence is ineffective; likewise, for a dumb terminal, "done." ends up on its own line. Aside from the noise, this also suggests making a special case for emacsclient.

And, as Junio pointed out in [2], with a message so long, once it has wrapped, the clear-line sequence does not work as intended. For those of us with 80-column terminals, we're left with a bunch of noise on the screen.

Show 17 quoted lines
> +                       fflush(stderr);
> +               }
>
>                 p.argv = args;
>                 p.env = env;
> @@ -53,11 +79,14 @@ int launch_editor(const char *path, struct strbuf *buffer, const char *const *en
>                 sig = ret - 128;
>                 sigchain_pop(SIGINT);
>                 sigchain_pop(SIGQUIT);
> +
>                 if (sig == SIGINT || sig == SIGQUIT)
>                         raise(sig);
>                 if (ret)
>                         return error("There was a problem with the editor '%s'.",
>                                         editor);
> +               if (close_notice)
> +                       fputs(close_notice, stderr);

Should printing of close_notice be done before the error()? Otherwise, you get this:

--- 8< --- Launched your editor (...) ...There was a problem... --- 8< ---

>         }

[1]: https://public-inbox.org/git/xmqqr2syvjxb.fsf@gitster.mtv.corp.google.com/ [2]: https://public-inbox.org/git/xmqqy3n4rbnr.fsf@gitster.mtv.corp.google.com/

Previous: Lars SchneiderNext: Junio C Hamano
Message 4 of 12 in “launch_editor(): indicate that Git waits for user input”
  1. launch_editor(): indicate that Git waits for user inputlars.schneider@autodesk.com, Nov 17, 2017
  2. Junio C HamanoNov 17, 2017
  3. Lars SchneiderNov 22, 2017
  4. Eric SunshineNov 17, 2017
  5. Junio C HamanoNov 18, 2017
  6. Kaartic SivaraamNov 19, 2017
  7. Junio C HamanoNov 20, 2017
  8. Lars SchneiderNov 22, 2017
  9. Kaartic SivaraamNov 22, 2017
  10. Junio C HamanoNov 24, 2017
  11. Lars SchneiderNov 22, 2017
  12. Eric SunshineNov 22, 2017

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