Re: MI & pretty-printing

Vladimir Prus
2009-07-15T12:19:16Z

On Tuesday 14 July 2009 Nick Roberts wrote:

> Vladimir Prus writes:
> >
> > On IRC, Tom and I talked about best way to support Python
> > pretty-printing with MI. Here's my attempt at summarizing.
> >
> > 1. It does not seem like existing frontends can make use of
> > pretty-printing automatically. If frontend tries to list
> > children of an invalid value, GDB may just hang. If GDB
> > automatically limits the number of children, then existing
> > frontends will not be able to see the children beyond this
> > limit (or have GUI for that). Therefore, it is suggested than
> > a new MI command is used to explicitly enable pretty-printing
> > in MI, say
> >
> > -enable-pretty-printing [0|1]
> >
> > 2. The FE may request a specific range of children by passing
> > low and high boundary:
> >
> > -var-list-children varobj [low] [hi]
>
> When I submitted patches for similar functionality in April/May
> of last year, I proposed a third parameter, stride, or step size,
> to sample a large array. ISTR Solaris dbx and Totalviewallow(ed) allow
> printing array slices in this way.
>
> first patch: http://sourceware.org/ml/gdb-patches/2008-04/msg00493.html
> final patch: http://sourceware.org/ml/gdb-patches/2008-05/msg00328.html

Right, I remember. However, I am still not sure were are ready for that addition.
We don't even have single range fully implemented *and* tested with real frontend.
Stride might be a good addition, but better not be done until we're done the current
round of changes.

> > If no range is specified, an attempt to report all children is
> > made, be what may.
> >
> > 3. A varobj keeps a range of children to fetch on -var-update, and
> > a new command is added to set that range, say,
> >
> > -var-set-update-range varobj low hi
>
> I think -var-set-update-range would be a useful addition.

OK.

- Volodya