Re: Re: [BGL] Best way to abort an algorithm from withi n a visitor?

From: Chris Russell (cdr_at_[hidden])
Date: 2002-09-18 15:54:48

I suppose you're right. Point well taken.

"Mark Storer" <mstorer_at_[hidden]> wrote in message
news:E840F0B7E6189547BDB91DA8BF2228AB016255F9_at_csmail.cardiff.com...
> Using exceptions in this way just bugs me.  Religious reasons I guess.  As
> the Esteemed Mr. Hylsop ;) mentioned earlier, exceptions are for "oops".
> This seems alot like the whole "do{}while(0)" with various 'break'
> statements sprinkled in to avoid multiple returns/nested ifs.  Useful, but
> Just Not Right.
>
> Your code has cooties!  Nobody's going to want to sit next to it during
> recess...
>
> >So there's no way to affect feedback to the algorithm's dispatcher
> >without actually making modifications to the algorithm code.
>
> So modify away.  Seems like a "breath_first_until" sort of thing would be
> quite useful.  Pass in some sort of predicate, and away you go.  I'm sure
> the community at large would be grateful.
>
> --Mark Storer
>   Software Engineer
>   Cardiff Software
>
> #include <disclaimer>
> typedef std::disclaimer<Cardiff> Discard;
>
>
> -----Original Message-----
> From: Chris Russell [mailto:cdr_at_[hidden]]
> Sent: Wednesday, September 18, 2002 1:27 PM
> To: boost-users_at_[hidden]
> Subject: [Boost-Users] Re: [BGL] Best way to abort an algorithm from
> withi n a visitor?
>
>
> > Now if you've got more than a hundred or so entries left to go,
exceptions
> > really are the greener grass.
> >
>
> The size of the graph is not known a-priori (not at coding time anyway)
but
> is likely to be quite large.
>
> > What's wrong with 'return', perhaps along-side some sort of 'done'
status
> > variable?  I'm only vaguely familiar with the visitor pattern, but these
> > would seem to be the obvious choice.
> >
>
> See my earlier reply. In this case I'm deriving my visitor from a base and
> overriding "event" handlers that receive their marching orders via const
> references and return void. So there's no way to affect feedback to the
> algorithm's dispatcher without actually making modifications to the
> algorithm code.
>
>
> "Mark Storer" <mstorer_at_[hidden]> wrote in message
> news:E840F0B7E6189547BDB91DA8BF2228AB016255F8_at_csmail.cardiff.com...
> > If efficiency is your goal, exceptions are not the answer.  Just
enabling
> > exceptions at compile time makes a noticable performance hit.  Actually
> > throwing an exception can gobble up a 1000 cycles, give or take.  That's
> per
> > throw.  If you catch and throw again, you'll pay again.
> >
> > Now if you've got more than a hundred or so entries left to go,
exceptions
> > really are the greener grass.
> >
> > What's wrong with 'return', perhaps along-side some sort of 'done'
status
> > variable?  I'm only vaguely familiar with the vistor pattern, but these
> > would seem to be the obvious choice.
> >
> > --Mark Storer
> >   Software Engineer
> >   Cardiff Software
> >
> > #include <disclaimer>
> > typedef std::disclaimer<Cardiff> Discard;
> >
>
>
>
>
>
>
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