Re: fun with hashes!

Uri Guttman wrote:
> > > > > > "AP" == A Pagaltzis <pagaltzis@xxxxxx> writes:
>   AP> * Jerrad Pierce <belg4mit@xxxxxxx> [2007-11-23 22:50]:
>   >> exists( $dispatch{$sub} ) ? $dispatch{$sub}->() :
>   >> warn "Key <$sub> does not exist in the dispatch table";
>
>   AP>     ( $dispatch{$sub} || sub { warn "no such action '$sub'" } )->();
>
> some variations on that:
>
>         my $sub = $dispatch{$key} or die "trying to call missing code" ;
>         $sub->() ;
>
> or:
>
>         my %dispatch = (
>                 foo     => \&foo,
>                 ...
>                 default => \&default
>         ) ;
>
>         $key = 'default' unless exists( $dispatch{ $key } ;
>         $sub = $dispatch{ $key } ;
>
> or:
>         my $sub = $dispatch{ $dispatch{ $key } ?
>                         $key : $dispatch{ 'default' } } ;
Shouldn't this be?

 my $sub = $dispatch{ $dispatch{ $key }
                    ? $key
                    : 'default'
                    };


> or:
>
>         my $sub = $dispatch{ $key } || $dispatch{ 'default' } ;
>
>
> as you can see there are various ways to handle a missing dispatch
> key. this is not a hash issue but a detail about doing dispatch tables
> cleanly. sometimes you want to predefine a default code ref in the
> dispatch table and other times you want to handle the missing key when
> you make the call through the dispatch table.
>
> uri
Or:

 my $sub = ( exists $dispatch{ $key } && ref( $dispatch{ $key } ) eq 'CODE' )
         ? $dispatch{ $key }
         : $dispatch{ 'default' };

Just because you're not paranoid doesn't mean computers don't hate you :)
--
Just my 0.00000002 million dollars worth,
 Shawn

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