guile support in gdb

guile support in gdb

[Tom Tromey]

Hi.

We were recently wondering (buried in a thread on the gdb-patches list)
whether the guile support in gdb actually works.  Does anybody use it
regularly?

If it doesn't work, I'd like to remove it.


FWIW, I think whatever guile-specific value-printing code there is in
gdb would be better rewritten as some python pretty-printers maintained
and distributed with guile itself.  That will reduce the chance of
bit-rotting.  (From what I can tell, this is actually the bulk of the
guile code in gdb that might actually work.)

Tom

Re: guile support in gdb

[Andy Wingo]

Hi Tom,

On Thu 07 Oct 2010 20:39, Tom Tromey <tromey@redhat.com> writes:

> We were recently wondering (buried in a thread on the gdb-patches list)
> whether the guile support in gdb actually works.  Does anybody use it
> regularly?

I can't speak for others, but I don't use it. We currently recommend
gdbinit files that define commands that call into libguile directly.

> FWIW, I think whatever guile-specific value-printing code there is in
> gdb would be better rewritten as some python pretty-printers maintained
> and distributed with guile itself.

I was actually hoping to get to extending GDB in guile at some point,
making Guile an acceptable language for GDB extensions.

What do you think? Would you accept a patch?

Andy
-- 
http://wingolog.org/

Re: guile support in gdb

[Tom Tromey]

>>>>> "Andy" == Andy Wingo <wingo@pobox.com> writes:

Andy> I can't speak for others, but I don't use it. We currently recommend
Andy> gdbinit files that define commands that call into libguile directly.

Thanks.  I will probably remove it, then.

Tom> FWIW, I think whatever guile-specific value-printing code there is in
Tom> gdb would be better rewritten as some python pretty-printers maintained
Tom> and distributed with guile itself.

Andy> I was actually hoping to get to extending GDB in guile at some point,
Andy> making Guile an acceptable language for GDB extensions.

Andy> What do you think? Would you accept a patch?

I think it is best for a project to have a single extension language.
So, I'm afraid my inclination would be not to accept it.

Tom

Re: guile support in gdb

[Ludovic Courtès]

Hi,

Tom Tromey <tromey@redhat.com> writes:

> We were recently wondering (buried in a thread on the gdb-patches list)
> whether the guile support in gdb actually works.  Does anybody use it
> regularly?
>
> If it doesn't work, I'd like to remove it.

I just tried, and here’s what I got:

--8<---------------cut here---------------start------------->8---
(gdb) set language scheme
(gdb) bt

[...]

#15 0x00007ffff5c22453 in internal_readline (text="scheme@(guile-user)> ", inp=
frame.c:1742: internal-error: get_frame_pc: Assertion `frame->next != NULL' failed.
A problem internal to GDB has been detected,
further debugging may prove unreliable.
Quit this debugging session? (y or n)
--8<---------------cut here---------------end--------------->8---

TEXT, which is a Scheme object, was successfully printed, but then
things went wrong.  :-)

Actually, I had made a few changes to reinstate (!) Guile support and
make some of the basics work a couple of years ago, but that was for
Guile 1.8.

Now the situation with 2.0 is different: as a Guile user I rarely need
to debug with gdb (more Scheme, less C!), and as a Guile developer I
often end up using ad hoc solutions.

Besides, I second Andy’s proposal to have Guile as an extension language
for gdb.

Thanks,
Ludo’.

Re: guile support in gdb

[Andy Wingo]

On Thu 07 Oct 2010 23:27, Tom Tromey <tromey@redhat.com> writes:

> Andy> I was actually hoping to get to extending GDB in guile at some point,
> Andy> making Guile an acceptable language for GDB extensions.
>
> I think it is best for a project to have a single extension language.
> So, I'm afraid my inclination would be not to accept it.

That's unfortunate. Guile is the GNU extension language, you know.

Andy
-- 
http://wingolog.org/

Re: guile support in gdb

[Tom Tromey]

>>>>> "Andy" == Andy Wingo <wingo@pobox.com> writes:

Andy> That's unfortunate. Guile is the GNU extension language, you know.

Yeah, I know.

While the decision to use Python was made before I was active in GDB
(look in the archives around Jan 2007 for the thread), and while I am
actually not a fan of Python, I do basically agree with this choice.  My
reason is that I think it is important to have a popular language with a
wide variety of available libraries.  Python is a very easy sell to
various GDB user communities.

Tom

Re: guile support in gdb

[Andy Wingo]

On Fri 08 Oct 2010 03:31, Tom Tromey <tromey@redhat.com> writes:

>>>>>> "Andy" == Andy Wingo <wingo@pobox.com> writes:
>
> Andy> That's unfortunate. Guile is the GNU extension language, you know.
>
> Yeah, I know.
>
> While the decision to use Python was made before I was active in GDB
> (look in the archives around Jan 2007 for the thread), and while I am
> actually not a fan of Python, I do basically agree with this choice.  My
> reason is that I think it is important to have a popular language with a
> wide variety of available libraries.  Python is a very easy sell to
> various GDB user communities.

Yeah, understood. Guile wasn't doing all that well either in 2007, so it
wasn't quite the obvious choice, and still has a ways to go before
popularity strikes; but otoh it does allow for other languages,
including javascript. Not that that support is really where I want it to
be yet..

Anyway, perhaps we will revisit this conversation in a couple years.

Happy hacking,

Andy
-- 
http://wingolog.org/