Re: RFC: selected frame in read_var_value

[Daniel Jacobowitz <drow at mvista dot com>]

On Fri, Sep 05, 2003 at 01:09:46PM -0400, Andrew Cagney wrote:
> >On Thu, Aug 07, 2003 at 01:45:28PM -0400, Andrew Cagney wrote:
> >
> >>>Thoughts on this?  I observed one case where the selected frame hadn't 
> >>been
> >>>initialized yet: when checking watchpoint values.  Oops!  The condition
> >>>matches the case in which get_current_frame () can be reasonably 
> >>expected >to
> >>>succeed.  There are a couple other places that need this same check, 
> >>mostly
> >>>functions which will work on globals as well as locals.
> >
> >>
> >>I think the caller, and not this code, should be the one deciding 
> >>if/when a get_selected_frame should be called.  Otherwize the dependance 
> >>on global state remains.
> >
> >
> >The callers don't know any more than we do.  Take a look at some of
> >them - several callers don't take frame arguments, and work both when
> >the program is running and when it isn't.  If you want to cut down on
> >the global state dependence, I guess you'd have to push this up through
> >every caller, so that it could eventually be pushed even higher?
> 
> Yep, welcome to my world :-)

Your world is a very strange place :)

> >Me, I was just fixing the regression caused by lazily selecting a
> >frame.  I wasn't planning on redesigning interfaces all through the
> >block and variable layers; and fixing this really does go quite far up.
> >For instance it works back to block_innermost_frame, which can return
> >NULL.
> 
> What about something like this as a step sideways:
> 
> >if (frame == NULL)
> >  frame = deprecated_safe_get_selected_frame ();
> 
> where deprecated_safe_get_selected_frame() would contain those sanity 
> checks?

Do you think this would interfere with fixing it later?  If not, I'll
put together a patch.

-- 
Daniel Jacobowitz
MontaVista Software                         Debian GNU/Linux Developer