MI & pretty-printing

[nickrob at snap dot net dot nz (Nick Roberts)]

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

 > 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.

-- 
Nick                                           http://www.inet.net.nz/~nickrob