Re: MI: type prefixes for values

[Daniel Jacobowitz <drow@false.org>]

On Thu, Apr 06, 2006 at 05:03:25PM +0400, Vladimir Prus wrote:
> I was thinking about this more, and still not 100% sure how Xcode can do this. 
> Do you mean that Xcode takes a stack trace when the varobj was created, and 
> deletes varobj whenever it sees that stack became shorter?
> 
> The case I'm not sure about is this:
> 
> 1. main calls 'a' which calls 'b' which bits breakpoint.
> 2  varobj is created for local var of 'b'
> 3. Users says 'continue'.
> 4. 'b' exists and then 'a' calls 'b' again and breakpoint is
>    hit again.
> 
> However, this second time it's not guaranteed that stack frame of 'b' is at 
> the same address as it was the last time -- maybe 'a' has pushed something on 
> stack. How do you detect this case?

Either b's stack frame is at the same address - in which case the
varobj is still valid - or else it isn't, in which case the frame id
has changed.

> > Note, however, that the varobj's do remember their frames, so if you
> > tried to evaluate one that was no longer on the stack, the varobj
> > would report "out of scope".
> 
> Would be great to add this in FSF version.

It's already there:

  /* The frame for this expression */
  struct frame_id frame;

c_value_of_root will always fail if the frame is gone.

-- 
Daniel Jacobowitz
CodeSourcery