Re: [FWP] Moment of Zen

[John Porter <jdporter@min.net>]

* Ronald J Kimball (rjk@linguist.dartmouth.edu) [991001 10:37]:
> On Fri, Oct 01, 1999 at 09:55:44AM -0400, John Porter wrote:
> > lr@hpl.hp.com wrote:
> > > 
> > > >     foreach $site (sort keys %sites) {
> > > >       #...
> > > >       my $mindshare = mindshare(...);
> > > >       $shares{$site} = $mindshare;
> > > >     }
> > > 
> > > Why an explicit (slow) loop?
> > > 
> > >       my %shares;
> > >       @shares{keys %sites} = map mindshare($_) => values %sites;
> > 
> > I realize the argument has shifted to performance... but, larry,
> > what you wrote isn't the same as the original.
> > I think you should have written
> > 
> >       my %shares;
> >       @shares{keys %sites} = map mindshare($_) => keys %sites;
> > 
> > Note the source for the map is keys %sites, not values %sites.
> > 
> > And I think this shifts the entire direction of how this code
> > can be optimized.
> > 
> 
> Neither code is the same as the original.  Code the same as the original
> cannot be benchmarked, because the original code is not complete!
> 
>       my $mindshare = mindshare(...);
> 
> We don't know what the arguments to mindshare() are. 

O.k., now you're the one who's being perticlar. :-)
It's pretty obvious that the arguments would include each key from %sites.


> Clearly, the loop is
> where optimization has to be focused.

Right; and that's where suggested optimizations *have* been focused.

-- 
John Porter


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