Re: Re-initializing a list after the control returns to gdb...

Andrew Cagney
2003-02-26T15:57:15Z

> [Sorry for answering late, got preempted...]
>
>
>> In hindsite, it needs to be converted to an observer model (or a new
>> observer model introduced and the current gdb-hooks changed to one of
>> the many observers).
>
>
> One model that works extremely well is the signals system implemented in
> glib. I find it very nicely done. It would be nice if we could reuse
> this, but this is a very very complex machinery doing probably way too
> much for what we need in GDB.

Yes. GDB just needs a single consistent event mechanism.

> I would instead suggest something much more simple, like this:
>
> enum notice_kinds
> {
> breakpoint_created_notice,
> breakpoint_deleted_notice,
> ...
> invalid_last_notice, /* Should always be last. */
> };

gdb-events.sh used individual wrapper functions rather than trusting an
enum, a void *, and dodgy casts. This was to ensure that the external
iterfaces were all strongly typed (calls checked with -Werror) and all
nasty casts were burried in the .c file.

It did that right.

It, however, made several mistakes:

- it tried to group all the events together (you've proposed individual
registration which is much more incremental)

- it didn't implement broadcast (as proposed here)

- `event' in GDB has multiple meanings so the name is confusing.

So, can you get a prototype observer working for just your ada event
(but keep in mind that other events will be boiler-plated)?

As for the names, just use the terminology found in the patterns book -
observer.[hc]. observer_update_xxx (or notify_xxx),
observer_attach_xxx, observer_detach_xxx I think. If GDB needs more
than one observer, there's a problem.

(oh, unless you've an immediate need for that data/context parameter,
i'd leave it out - such a mechanis can be left to the person that
actually needs)

(shh, doco - but I have a cunning plan - see my recent post about
revamping gdbarch.sh into doc/gdbarch.texi).

Andrew