Re: fun with hashes!

Uri Guttman wrote:
>>>>>> "AP" == A Pagaltzis <[email protected]> writes:
> 
>   AP> * Jerrad Pierce <[email protected]> [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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