Dash Archive mirror
 help / color / mirror / Atom feed

From: "anonymous4feedback@outlook.com" <anonymous4feedback@outlook.com>
To: unlisted-recipients:; (no To-header on input)
Cc: "dash@vger.kernel.org" <dash@vger.kernel.org>
Subject: 回复: Bug in dash: Incorrect behaviour of $LINENO in function
Date: Sat, 14 Jan 2023 10:55:39 +0000	[thread overview]
Message-ID: <PS2PR03MB38306209EFE7E00A8B49CE9F92C39@PS2PR03MB3830.apcprd03.prod.outlook.com> (raw)

Sorry I didn't explain this clearly, and I made some wrong assumption in the first email.

I made another simpler test

# line 1 is empty
# line 2 is empty
foo(){ # line 2
  echo $LINENO; } # line 3
foo # line 4

dash prints 2, (line number in function, counting from 1)
bash and ksh prints 4, (line number in whole script)
and zsh prints 1 (line number in function, counting from 0)

More test moving the lines around confirms the guess in parens.

Can I say that none of these is wrong because there is no standard about this?


发件人: Marc Chantreux <mc@unistra.fr>
发送时间: 2023年1月14日 17:39
收件人: anonymous4feedback@outlook.com <anonymous4feedback@outlook.com>
抄送: dash@vger.kernel.org <dash@vger.kernel.org>
主题: Re: Bug in dash: Incorrect behaviour of $LINENO in function 
 
hello,

> It seems dash stores the line number of the parameter substitution and the line number of the function definition

which is what we expect from a variable expansion. what you need here
is an alias because it works like a minimal but dynamic preprocessor

those are the tricks about aliases:

* they really act as a preprocessor so

        alias warn='>&2 echo here at $LINENO'
        f() warn first
        alias warn='>&2 echo another message at $LINENO'
        g() warn last
        f;g

        # does

        here at 1 first
        another message at 1 last

* interpolation comes first so 

        entering() {
                echo entering "$@"
                "$@"
        }
        f() echo doing things in functions
        alias damn='echo oops ...'
        entering f
        entering damn

        entering f
        doing things in functions
        entering damn
        /home/mc/src/vendor/dash/src/dash: 3: damn: not found

conclusion:

* use functions as long as you can
* in this case, you can't. your solution is

        alias warn='>&2 echo here at $LINENO'

HTH,
Marc Chantreux

next             reply	other threads:[~2023-01-14 10:55 UTC|newest]

Thread overview: 4+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2023-01-14 10:55 anonymous4feedback [this message]
  -- strict thread matches above, loose matches on Subject: below --
2023-01-14  5:30 Bug in dash: Incorrect behaviour of $LINENO in function anonymous4feedback
2023-01-14  9:39 ` Marc Chantreux
2023-01-14 10:57   ` 回复: " anonymous4feedback
2023-01-14 11:10     ` Harald van Dijk
2023-01-14 13:52       ` Marc Chantreux

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=PS2PR03MB38306209EFE7E00A8B49CE9F92C39@PS2PR03MB3830.apcprd03.prod.outlook.com \
    --to=anonymous4feedback@outlook.com \
    --cc=dash@vger.kernel.org \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link

This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for read-only IMAP folder(s) and NNTP newsgroup(s).