Re: [Foxgui-users]Re: [Foxgui-announce]New snapshot (experimental)

[Jeroen v. d. Z. <je...@fo...>]

On Friday 24 September 2004 11:15 am, Lothar Scholz wrote:
> Hello Niall,
> 
> ND> Exception throwing code, if it is to work correctly at all, requires
> ND> a very different style of design and implementation. Grafting it onto
> ND> code not written with it in mind gives the illusion that graceful 
> ND> recovery from exception throws works when in fact it may only do so
> ND> some of the time under special conditions. Even the world's best C++
> ND> programmers find it tough to get exception unwinding to work in code
> ND> written specifically for it - ask STL implementors.
> 
> Right, that is the reason why a lot of languages simply don't handle out
> of memory errors - most famous of course Java.
> And this seems good, otherwise the overhead at least in a language
> without GC like C++ is terrible high.
> 
> So i would simply don't care about this and only add some handler for
> a coordinated crash (saving data before, putting up a dialog etc).
> 
> If you run out of memory, you should really move to another fault
> handling level, like having a super process.
> 
> 

Doing it right with exceptions is difficult.  The strategy I'm following
is based on the idea of "checkpoints".

Every time you do a callback, you get further into the computation; however,
we know we were still OK before the callback, so that is a point to
which we can safely back up.

In interactive programs, nothing happens except in response to a callback,
to putting the try{ } catch () {} around that seemed like a good start;
it will probably be refined over time, since some exceptions should indeed
propagate up, and others not.


I'm open to suggestions; however, the bottom line is that this time, exceptions
are likely here to stay; we're really just debating how far we'll go with this.

At any rate, the current snapshot would cover a big part of the resource problems
people are likely to encounter.  So I believe its a good step forward to
having applications deal with resource issues gracefully.  


BTW, any progress on the sizeof() questions with in FXThread?


	- Jeroen