Re: Reference/Alias inner hash section

The easy problem first: You've misspelled $update. Of all times, the time use strict; and use warnings; are needed the most is when hunting bugs. Use them!!

$h contains a reference to a scalar, the value at $a{$state}{$city}. You need to deference it before you can do anything with the referenced value.

$a{$state}->{$city}->{Color} = $color;

          ===

${ \( $a{$state}->{$city} ) }->{Color} = $color;

     # For every reference added,
     # a dereference must be added.

          ===

my $r = \( $a{$state}->{$city} );
${ $r }->{Color} = $color;
[download]

Comment on Re: Reference/Alias inner hash section Select or Download Code

Replies are listed 'Best First'.
Re^2: Reference/Alias inner hash section by mpettis (Beadle) on Sep 09, 2008 at 00:21 UTC
Oh fer cryin' out loud -- thanks, both of you. Try to mock up a quick stripped-down version, and I shoot myself in the foot. Thanks again, Matt	[reply]
Re^3: Reference/Alias inner hash section by ikegami (Patriarch) on Sep 09, 2008 at 00:28 UTC
The difference between `# broomduster my $h = $a{$state}{$city}; $h->{'Color'} = $color;` [download] and `# ikegami my $r = \( $a{$state}->{$city} ); ${ $r }->{Color} = $color;` [download] is that only the latter autovivifies if necessary. For example, here's what happens if `$a{'WI'}{'GreenBay'}{'Color'} = 'Black';` [download] is commented out: `# broomduster $VAR1 = { 'WI' => {} };` [download] `# ikegami $VAR1 = { 'WI' => { 'GreenBay' => { 'Color' => 'White' } } };` [download] The following would also do: `my $h = $a{$state}{$city} \|\|= {}; $h->{'Color'} = $color;` [download]	[reply] [d/l] [select]
Re^4: Reference/Alias inner hash section by mpettis (Beadle) on Sep 09, 2008 at 00:39 UTC
Thanks ikegami, autovivification was an issue -- I started out using broomduster's method, but set the sub-hash to '{}' if the hash keys didn't exist. Your method is more compact. Thanks, Matt	[reply]