On Thu, Jul 28, 2016 at 1:47 PM, Johannes Sixt <j6t@xxxxxxxx> wrote:
> Interactive rebase uses 'wc -l' to write the current patch number
> in a progress report. Some implementations of 'wc -l' produce spaces
> before the number, leading to ugly output such as
>
> Rebasing ( 3/8)
>
> Remove the spaces using a trivial arithmetic evaluation.
>
> Before 9588c52 (i18n: rebase-interactive: mark strings for
> translation) this was not a problem because printf was used to
> generate the text. Since that commit, the count is interpolated
> directly from a shell variable into the text, where the spaces
> remain. The total number of patches does not have this problem
> even though it is interpolated from a shell variable in the same
> manner, because the variable is set by an arithmetic evaluation.
>
> Later in the script, there is a virtually identical case where
> leading spaces are trimmed, but it uses a pattern substitution:
>
> todocount=$(git stripspace --strip-comments <"$todo" | wc -l)
> todocount=${todocount##* }
>
> I did not choose this idiom because it adds a line of code, and
> there is already an arithmetic evaluation in the vicinity of the
> line that is changed here.
On the other hand, to a newcomer (not familiar with this patch),
${foo##* } is an obvious and intentional stripping of whitespace,
whereas taking advantage of a side-effect of arithmetic evaluation to
achieve the same is quite subtle and likely to be interpreted as
pointless, thus forces the reader to consult 'blame' to understand why
the code is the way it is.
> Signed-off-by: Johannes Sixt <j6t@xxxxxxxx>
> ---
> diff --git a/git-rebase--interactive.sh b/git-rebase--interactive.sh
> @@ -121,7 +121,7 @@ mark_action_done () {
> sed -e 1q < "$todo" >> "$done"
> sed -e 1d < "$todo" >> "$todo".new
> mv -f "$todo".new "$todo"
> - new_count=$(git stripspace --strip-comments <"$done" | wc -l)
> + new_count=$(( $(git stripspace --strip-comments <"$done" | wc -l) ))
> echo $new_count >"$msgnum"
> total=$(($new_count + $(git stripspace --strip-comments <"$todo" | wc -l)))
> echo $total >"$end"
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