Re: MI & pretty-printing

[Vladimir Prus <vladimir@codesourcery.com>]

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