Thread (2 messages) flat view 2 messages, 2 authors, 2016-06-15

Re: [PATCH 1/2] Allow __git_ps1 to be used in PROMPT_COMMAND

From: Junio C Hamano <hidden>
Date: 2016-06-15 22:54:58

Simon Oosthoek [off-list ref] writes:
changes __git_ps1 to not just allow use in setting PS1
with __git_ps1 in a command substitution, but also allows
__git_ps1 to be used as PROMPT_COMMAND in bash.
This has advantages for using color and I think it is more
elegant
Is "and I think" necessary?  I do not think it matters what _you_
think when judging it is worth including in the future releases ;-)

A lot more important thing to say is why it has advantages for using
color (remember, it took a few rounds of back and forth with me).
Unless you are going to explain the same to all the people who are
reading the "git log" output 6 months down the road, that is a more
appropriate thing to write here.
quoted hunk
 contrib/completion/git-prompt.sh |   51 +++++++++++++++++++++++++++++++++-----
 1 file changed, 45 insertions(+), 6 deletions(-)
diff --git a/contrib/completion/git-prompt.sh b/contrib/completion/git-prompt.sh
index 29b1ec9..c50c94a 100644
--- a/contrib/completion/git-prompt.sh
+++ b/contrib/completion/git-prompt.sh
@@ -10,9 +10,14 @@
 #    1) Copy this file to somewhere (e.g. ~/.git-prompt.sh).
 #    2) Add the following line to your .bashrc/.zshrc:
 #        source ~/.git-prompt.sh
-#    3) Change your PS1 to also show the current branch:
-#         Bash: PS1='[\u@\h \W$(__git_ps1 " (%s)")]\$ '
-#         ZSH:  PS1='[%n@%m %c$(__git_ps1 " (%s)")]\$ '
+#    3a) In ~/.bashrc set PROMPT_COMMAND=__git_ps1
+#        To customize the prompt, provide start/end arguments
+#        PROMPT_COMMAND="__git_ps1 '\u@\h:\w (' ')\$ '"
+#    3b) Alternatively change your PS1 to call __git_ps1 as
+#        command-substitution:
+#        Bash: PS1='[\u@\h \W$(__git_ps1 " (%s)")]\$ '
+#        ZSH:  PS1='[%n@%m %c$(__git_ps1 " (%s)")]\$ '
+#        the optional argument will be used as format string
 #
 # The argument to __git_ps1 will be displayed only if you are currently
 # in a git repository.  The %s token will be the name of the current
@@ -194,11 +199,41 @@ __git_ps1_show_upstream ()
 
 
 # __git_ps1 accepts 0 or 1 arguments (i.e., format string)
+# when called from PS1 using command substitution
+# in this mode it returns text to add to bash PS1 prompt (includes branch name) or
+# __git_ps1 accepts 0 or 2 arguments when called from PROMPT_COMMAND
+# in that case it _sets_ PS1. The arguments are parts of a PS1 string.
+# when both arguments are given, the first is prepended and the second appended
+# to the state string when assigned to PS1, otherwise default start/end strings
+# are used.
Sorry, but I cannot parse this.  Is this meant to be a two-item list,
one describing the command substitution mode (zero or 1 arguments) and
the other describing the prompt command mode?  If so, perhaps replacing
the " or" at the end of the first item with ".\n#\n" would make it readable.
 __git_ps1 ()
 {
+	local pcmode=yes
+	local ps1pc_start='\u@\h:\w '
+	local ps1pc_end='\$ '
+
+	case "$PROMPT_COMMAND" in
+		__git_ps1*)
+			if [ $# = 2 ]; then
+				ps1pc_start="$1"
+				ps1pc_end="$2"
+			fi
+			case "$PS1" in
+			*__git_ps1*)
+				echo '__git_ps1: overwriting PS1 due to PROMPT_COMMAND'
Is this supposed to be an error and/or warning message?  Why is it
worth warning only when you are overwriting __git_ps1 style of PS1
and not other user customization?
+			;;
+			esac
+		;;
+		*)  pcmode=no ;; #no output
+	esac
Please align outer "case" "its arms)" and "esac" at the same column,
like you did for the inner "case/esac".

Auto-detetction based on PROMPT_COMMAND is a flaky approach.  In
practice, nobody will call PROMPT_COMMAND with the __git_ps1 without
any parameter (100% people want their prompt to end with some sort
of whitespace so they want the "what comes after what is computed",
aka $2), and even more importantly, nobody has been relying on use
of 0 argument form of __git_ps1 in PROMPT_COMMAND.  So why not
always require 2 args and take that as a cue to go into the pc mode?
quoted hunk
+
 	local g="$(__gitdir)"
-	if [ -n "$g" ]; then
+	if [ -z "$g" ]; then
+		if [ $pcmode = yes ]; then
+			#In PC mode PS1 always needs to be set
+			PS1="$ps1pc_start$ps1pc_end"
+		fi
+	else
 		local r=""
 		local b=""
 		if [ -f "$g/rebase-merge/interactive" ]; then
@@ -284,6 +319,10 @@ __git_ps1 ()
 		fi
 
 		local f="$w$i$s$u"
-		printf -- "${1:- (%s)}" "$c${b##refs/heads/}${f:+ $f}$r$p"
+		if [ $pcmode = yes ]; then
+			PS1="$ps1pc_start($c${b##refs/heads/}${f:+ $f}$r$p)$ps1pc_end"
+		elif [ $pcmode = no ]; then
+			printf -- "${1:- (%s)}" "$c${b##refs/heads/}${f:+ $f}$r$p"
+		fi
Are there $pcmode other than yes or no?  Why not just "else",
instead of performing the test twice?
 	fi
 }
Keyboard shortcuts
hback out one level
jnext message in thread
kprevious message in thread
ldrill in
Escclose help / fold thread tree
?toggle this help