Re: Feature Request: Allow skipping zsh statement on return from trap DEBUG

[Rocky Bernstein <rocky.bernstein@xxxxxxxxx>]

My apologies for not realizing this. I _did_ look at the trap DEBUG command
and even noticed the DEBUG_BEFORE_CMD, but I guess I didn't read carefully
enough to notice ERR_EXIT.

At any rate with commit
https://github.com/rocky/zshdb/commit/d3f00505f58ddb3d781a2140d92baa19dcc0a200
(and the one before that) this is now all in the debugger, and it works
great!

When I get a chance, a new release, 1.1.0, will go out soon with this in
it.

Thanks, yet again, to Stephane for helping me out here.

-- 
I make mistakes, that's why I work on debuggers.


On Fri, Oct 25, 2019 at 1:52 PM Stephane Chazelas <
stephane.chazelas@xxxxxxxxx> wrote:

> 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
>