From: Stephane Chazelas <stephane.chazelas@gmail.com>
To: Rocky Bernstein <rocky.bernstein@gmail.com>
Cc: zsh-workers@zsh.org
Subject: Re: Feature Request: Allow skipping zsh statement on return from trap DEBUG
Date: Fri, 25 Oct 2019 18:52:06 +0100 [thread overview]
Message-ID: <20191025175206.7lpnhzcenlwqs4el@chaz.gmail.com> (raw)
In-Reply-To: <CANCp2gbJs=hW_Pu1AKAKDwhN_5LpFcVG634TGkpas5VDbg8nWg@mail.gmail.com>
2019-10-24 16:17:27 -0400, Rocky Bernstein:
> A while ago I wrote a debugger for zsh called zshdb
> <https://zshdb.readthedocs.io/en/latest/>. See also
> https://repology.org/project/zshdb/versions .
>
> A feature that is missing in the debugger and that is available in the
> corresponding debugger for bash, bashdb, is the skip command.
>
> This command skips over the upcoming statement to be executed. The way this
> works in bashdb, is that if the debug hook returns with a nonzero value.
> The way BASH works is that if the trap DEBUG hook returns a nonzero value,
> BASH skips statement to be run.
>
> Thoughts about extening zsh so that it too will skip the upcoming statement
> if the zsh trap DEBUG hook return a non-zero value. Or more generally some
> means by which a DEBUG hook can indicate to zsh to skip the upcoming
> statement?
[...]
See info zsh trap:
} If SIG is DEBUG then ARG will be executed before each command if
} the option DEBUG_BEFORE_CMD is set (as it is by default), else
} after each command. Here, a 'command' is what is described as a
} 'sublist' in the shell grammar, see *note Simple Commands &
} Pipelines::. If DEBUG_BEFORE_CMD is set various additional
} features are available. First, it is possible to skip the next
} command by setting the option ERR_EXIT; see the description of the
} ERR_EXIT option in *note Description of Options::. Also, the shell
} parameter ZSH_DEBUG_CMD is set to the string corresponding to the
} command to be executed following the trap. Note that this string
} is reconstructed from the internal format and may not be formatted
} the same way as the original text. The parameter is unset after
} the trap is executed.
Was added in 2008: https://www.zsh.org/mla/workers/2008/msg01075.html
You participated in that discussion, sounds likely you actually
requested the feature then.
TRAPDEBUG() {
echo "$ZSH_DEBUG_CMD"
[[ $ZSH_DEBUG_CMD = *x* ]] && set -o errexit
}
echo x
echo y
gives:
echo x
echo y
y
--
Stephane
next prev parent reply other threads:[~2019-10-25 17:52 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-10-24 20:17 Rocky Bernstein
2019-10-25 17:52 ` Stephane Chazelas [this message]
2019-10-26 1:37 ` Rocky Bernstein
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