Re: starting gdb/mi from FE

[Nick Roberts <nickrob@snap.net.nz>]

B> > > $This change is backwards compatible because users were not able in the 
 > > > $past to have a comma separated list in the -i flag.
 > > 
 > > Backward compatible because it won't work with any version before GDB 6.5?
 > 
 > Backward compatible because FE's can use mi2 when they do mi2, and
 > mi3,mi2 when they do more than mi2. I'm thinking no front end will ever
 > support mi1 (correct me if I'm wrong). Therefore, if we do this now,
 > it'll work for most FE's.

But it won't work for *released* versions of GDB.

 >...
 > > Pre GDB 6.5 wouldn't really work in this case either, but
 > > 
 > >   (gdb)
 > >   -mi-version
 > >   ^error,msg="Undefined MI command: mi-version"
 > >   (gdb)
 > > 
 > > wouldn't require restarting GDB, while:
 > > 
 > >   nickrob/21 gdb -i=mi2,mi1 myprog
 > >   Interpreter `mi2,mi1' unrecognized
 > >   nickrob/22
 > > 
 > > would.
 > 
 > That's not correct. Unless you will work with mi1. It will work with mi2
 > on as described above. 

I don't see how, unless you plan to `recall' all released versions of GDB.

 >                        Also, the solution your provide is a chicken/egg 
 > problem. If anyone ever changes the MI output syntax in a non backwards 
 > compatible way, then I will not know which generated parser to use. If I
 > don't know which generated parser to use, I can't possible call
 > -mi-version and expect to parse the output.

If it changes from:

(gdb)
-mi-version
^done,major="3",minor="1"
(gdb)

your right, but I think this part of MI should be pretty constant.  I imagine
MI level changes involving things like asynchronous operation, event
notification etc.

 >                                                I think it's bad to provide
 > functionality that only works with makeshift parsers.

I think we need to be practical and work within our limited resources.  If
a corporate sponsor comes along then maybe we can consider such general
principles.

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