requires: re-use vfs.tryread for simplicity
Avoids calling `set` twice or having to re-raise an exception and implements the routine with a single return expression.
Test alignment of multibyte characters
$ HGENCODING=utf-8
$ export HGENCODING
$ hg init t
$ cd t
$ "$PYTHON" << EOF
> from mercurial import pycompat
> # (byte, width) = (6, 4)
> s = b"\xe7\x9f\xad\xe5\x90\x8d"
> # (byte, width) = (7, 7): odd width is good for alignment test
> m = b"MIDDLE_"
> # (byte, width) = (18, 12)
> l = b"\xe9\x95\xb7\xe3\x81\x84\xe9\x95\xb7\xe3\x81\x84\xe5\x90\x8d\xe5\x89\x8d"
> f = open('s', 'wb'); f.write(s); f.close()
> f = open('m', 'wb'); f.write(m); f.close()
> f = open('l', 'wb'); f.write(l); f.close()
> # instant extension to show list of options
> f = open('showoptlist.py', 'wb'); f.write(b"""# encoding: utf-8
> from mercurial import registrar
> cmdtable = {}
> command = registrar.command(cmdtable)
>
> @command(b'showoptlist',
> [(b's', b'opt1', b'', b'short width' + (b' ' +%(s)s) * 8, %(s)s),
> (b'm', b'opt2', b'', b'middle width' + (b' ' + %(m)s) * 8, %(m)s),
> (b'l', b'opt3', b'', b'long width' + (b' ' + %(l)s) * 8, %(l)s)],
> b'')
> def showoptlist(ui, repo, *pats, **opts):
> '''dummy command to show option descriptions'''
> return 0
> """ % {b's': pycompat.byterepr(s),
> b'm': pycompat.byterepr(m),
> b'l': pycompat.byterepr(l),
> })
> f.close()
> EOF
$ S=`cat s`
$ M=`cat m`
$ L=`cat l`
alignment of option descriptions in help
$ cat <<EOF > .hg/hgrc
> [extensions]
> ja_ext = `pwd`/showoptlist.py
> EOF
check alignment of option descriptions in help
$ hg help showoptlist
hg showoptlist
dummy command to show option descriptions
options:
-s --opt1 \xe7\x9f\xad\xe5\x90\x8d short width \xe7\x9f\xad\xe5\x90\x8d \xe7\x9f\xad\xe5\x90\x8d \xe7\x9f\xad\xe5\x90\x8d \xe7\x9f\xad\xe5\x90\x8d \xe7\x9f\xad\xe5\x90\x8d \xe7\x9f\xad\xe5\x90\x8d \xe7\x9f\xad\xe5\x90\x8d \xe7\x9f\xad\xe5\x90\x8d (esc)
-m --opt2 MIDDLE_ middle width MIDDLE_ MIDDLE_ MIDDLE_ MIDDLE_ MIDDLE_
MIDDLE_ MIDDLE_ MIDDLE_
-l --opt3 \xe9\x95\xb7\xe3\x81\x84\xe9\x95\xb7\xe3\x81\x84\xe5\x90\x8d\xe5\x89\x8d long width \xe9\x95\xb7\xe3\x81\x84\xe9\x95\xb7\xe3\x81\x84\xe5\x90\x8d\xe5\x89\x8d \xe9\x95\xb7\xe3\x81\x84\xe9\x95\xb7\xe3\x81\x84\xe5\x90\x8d\xe5\x89\x8d \xe9\x95\xb7\xe3\x81\x84\xe9\x95\xb7\xe3\x81\x84\xe5\x90\x8d\xe5\x89\x8d (esc)
\xe9\x95\xb7\xe3\x81\x84\xe9\x95\xb7\xe3\x81\x84\xe5\x90\x8d\xe5\x89\x8d \xe9\x95\xb7\xe3\x81\x84\xe9\x95\xb7\xe3\x81\x84\xe5\x90\x8d\xe5\x89\x8d \xe9\x95\xb7\xe3\x81\x84\xe9\x95\xb7\xe3\x81\x84\xe5\x90\x8d\xe5\x89\x8d \xe9\x95\xb7\xe3\x81\x84\xe9\x95\xb7\xe3\x81\x84\xe5\x90\x8d\xe5\x89\x8d (esc)
\xe9\x95\xb7\xe3\x81\x84\xe9\x95\xb7\xe3\x81\x84\xe5\x90\x8d\xe5\x89\x8d (esc)
(some details hidden, use --verbose to show complete help)
$ rm -f s; touch s
$ rm -f m; touch m
$ rm -f l; touch l
add files
$ cp s $S
$ hg add $S
$ cp m $M
$ hg add $M
$ cp l $L
$ hg add $L
commit(1)
$ echo 'first line(1)' >> s; cp s $S
$ echo 'first line(2)' >> m; cp m $M
$ echo 'first line(3)' >> l; cp l $L
$ hg commit -m 'first commit' -u $S
commit(2)
$ echo 'second line(1)' >> s; cp s $S
$ echo 'second line(2)' >> m; cp m $M
$ echo 'second line(3)' >> l; cp l $L
$ hg commit -m 'second commit' -u $M
commit(3)
$ echo 'third line(1)' >> s; cp s $S
$ echo 'third line(2)' >> m; cp m $M
$ echo 'third line(3)' >> l; cp l $L
$ hg commit -m 'third commit' -u $L
check alignment of user names in annotate
$ hg annotate -u $M
\xe7\x9f\xad\xe5\x90\x8d: first line(2) (esc)
MIDDLE_: second line(2)
\xe9\x95\xb7\xe3\x81\x84\xe9\x95\xb7\xe3\x81\x84\xe5\x90\x8d\xe5\x89\x8d: third line(2) (esc)
check alignment of filenames in diffstat
$ hg diff -c tip --stat
MIDDLE_ | 1 +
\xe7\x9f\xad\xe5\x90\x8d | 1 + (esc)
\xe9\x95\xb7\xe3\x81\x84\xe9\x95\xb7\xe3\x81\x84\xe5\x90\x8d\xe5\x89\x8d | 1 + (esc)
3 files changed, 3 insertions(+), 0 deletions(-)
add branches/tags
$ hg branch $S
marked working directory as branch \xe7\x9f\xad\xe5\x90\x8d (esc)
(branches are permanent and global, did you want a bookmark?)
$ hg tag $S
$ hg book -f $S
$ hg branch $M
marked working directory as branch MIDDLE_
$ hg tag $M
$ hg book -f $M
$ hg branch $L
marked working directory as branch \xe9\x95\xb7\xe3\x81\x84\xe9\x95\xb7\xe3\x81\x84\xe5\x90\x8d\xe5\x89\x8d (esc)
$ hg tag $L
$ hg book -f $L
check alignment of branches
$ hg branches
\xe9\x95\xb7\xe3\x81\x84\xe9\x95\xb7\xe3\x81\x84\xe5\x90\x8d\xe5\x89\x8d 5:d745ff46155b (esc)
MIDDLE_ 4:9259be597f19 (inactive)
\xe7\x9f\xad\xe5\x90\x8d 3:b06c5b6def9e (inactive) (esc)
default 2:64a70663cee8 (inactive)
check alignment of tags
$ hg tags
tip 5:d745ff46155b
\xe9\x95\xb7\xe3\x81\x84\xe9\x95\xb7\xe3\x81\x84\xe5\x90\x8d\xe5\x89\x8d 4:9259be597f19 (esc)
MIDDLE_ 3:b06c5b6def9e
\xe7\x9f\xad\xe5\x90\x8d 2:64a70663cee8 (esc)
check alignment of bookmarks
$ hg book
MIDDLE_ 5:d745ff46155b
\xe7\x9f\xad\xe5\x90\x8d 4:9259be597f19 (esc)
* \xe9\x95\xb7\xe3\x81\x84\xe9\x95\xb7\xe3\x81\x84\xe5\x90\x8d\xe5\x89\x8d 5:d745ff46155b (esc)