Re: [PATCH v2 2/5] gdb: prevent prefix commands from being hooks

[Marco Barisione <mbarisione@undo.io>]

On 8 Mar 2021, at 21:32, Simon Marchi <simon.marchi@polymtl.ca> wrote:
> Ahhh, changes that touch command handling are always scary stuff, we
> need to be really careful not to break existing use cases or paint
> ourselves in corners for future use cases.  Probably why nobody dares to
> review it.  I'll give it a try, but know that it still scares me :).

It did scare me and took a while because of the many corner cases,
difficult combinations of features.

My reasoning behind this is that the behaviour is currently confusing
(that is, what the user would expect doesn’t happen) and forbidding
this should allow changes in the future quite easily.

> One question that pops up is, what if someone ever wants to make a hook
> for a prefixed command.  For example, let's say I want to hook "info
> inferiors".  I don't think that's possible today, but let's say we want
> to make it possible.  How would that work?
> 
> This doesn't work:
> 
>   (gdb) define hook-info inferiors
>    Undefined command: "hook-info".  Try "help".
> 
> So... maybe defining "hook-info" as a prefix command would allow it?
> Not sure, I didn't really think this through, but I wonder if you
> thought about that case.

You can do it with “define info hook-inferiors” which I found a bit
surprising when I discovered it.


I think that hooks are incredibly useful but limited. My hope is that
my patch series will make them less needed as you can get a better and
more powerful behaviour with command renaming.

-- 
Marco Barisione