RE: -var-update using formatted value

["Marc Khouzam" <marc dot khouzam at ericsson dot com>]

> > However, and I'm sorry for not letting this go, but what is the point of 
> > -var-update returning the list of changed variables, if it is so efficient
> > to go back to GDB to ask for values?  var-update might as well return nothing
> > and the let the front-end ask for values again.
> > (which is what I'll have to do if I can't cache all formats)
> 
> -var-update reads values from the target to check for changes.
> -var-update-expression and -var-set-format do not.  If you do not
> -var-update nothing will ever appear to change.

I'm not questioning var-update.  It is a must after the program has resumed.
But why does var-update actually report the changed variables to the front-end?
Why not just report "done"?
If var-update tells the front-end which variables have changed, it is for the 
front-end to know which ones it should use -var-evaluate-expression on
(say --no-values is used for var-update).  The front-end then does not need
to use -var-evaluate-expression on -all- displayed variables.

In my case, since I display all formats (sometimes), I need to do 
var-evaluate-expression on every displayed variable, since var-update won't 
properly tell me which variable really changed (in the case of float and strings).