Re: Variable identification

[Michael Snyder <msnyder@specifix.com>]

On Fri, 2007-11-30 at 17:38 -0800, Jim Blandy wrote:
> Michael Snyder <msnyder at specifix.com> writes:
> > On Thu, 2007-11-29 at 22:02 +0300, Vladimir Prus wrote:
> >> Jim Blandy wrote:
> >> 
> >> >> This is probably good behaviour, indeed. Or maybe we should not
> >> >> disable watchpoint, but mark it as pending, in the same sense of
> >> >> "user wanted it to be enabled, but it won't trigger until a shared
> >> >> lib is loaded" that is used for ordinary watchpoints.
> >> > 
> >> > I think so, too.  I guess the key observation is that, while it's not
> >> > meaningful to talk about a particular local variable "coming back
> >> > alive", since each function call creates a distinct set of local
> >> > variables, and you can have recursion, etc., it is meaningful to talk
> >> > about a shared library being reloaded, and it's intuitive to identify
> >> > the 'X' from the first loading with the 'X' in the second loading,
> >> > even if they're at different addresses.
> >> 
> >> Yes. I now recall this is more general problem with identification of
> >> variables in GDB. Say, you're in function, and you have local variable
> >> 'foo'. In GUI, you do something with 'foo' -- set display format to
> >> hex, expand it, and so on. It's highly desirable to keep this
> >> information for the next run of program, or even next run of the GUI --
> >> even if variable is local, it's not likely that the display properties
> >> user wants depend on frame.
> >> 
> >> Unfortunately, there's no way to do that.
> >
> > I haven't followed the discussion closely, but
> > shouldn't it be up to the GUI to keep such persistant
> > info?  It's nothing to do with gdb, really.  It's the
> > GUI's state.
> 
> These questions all affect how watchpoints behave in the CLI as well.

Right, with the CLI being a special case of "the GUI" -- one
in which we (gdb maintainers) have control of everything.

GDB can keep track of the CLI "state", but other GUI 
should keep track of their own state.