Re: Olson <-> Microsoft mappings

[Rick Measham]

 > It's become painfully obvious that having end users choose
 a timezone based on the huge list that is provided natively
 by DateTime::TimeZone::all_names just isn't very practical
 at this time.  (Perhaps in the future when more people are
 used to dealing with the Olson names.)
<snip>

 Is there anyway to do some work on TimeZoneCatalog to get some
 different kinds of lists (for instance, a shortened list of
 timezones that removes zones that only have historical differnces)?
 Would anyone be opposed to/in favor of that?

At 10:31 PM -1000 22/9/03, Joshua Hoblitt replied:
I think you want DateTime::TimeZone::names_in_category().  Which 
accepts a scalar from the array returned by categories() and itself 
returns a list of Olson timezones.
Maybe there should be a method to get the list of zones as a 
Hash-of-Hashes-of-Hashes such that we have:

$time_zones = {
        'Oceania' => {
                'Australia' => {
                        Melbourne => 'Australia/Melbourne',
                        Sydney    => 'Australia/Sydney',
                },
                'New Zealand' => {
                        Auckland  => 'NewZealand/Auckland',
                },
        },
        'North America' => {
                'United States' => {
                        'New York' => 'America/NewYork',
                },
        }
}
This would mean that we have tree data that can be used in forms. 
This code will turn it into a HTML select:

function make_select {
my %time_zones = (ref $_[0]) ? %{$_[0]} : @_;
foreach my $key ( sort keys %time_zones ) {
  if (ref $time_zones{$key}) {
    print qq|\t<optgroup label="$key">\n|;
    foreach my $subkey( sort keys %{$time_zones{$key}} ) {
      if (ref $time_zones{$key}{$subkey}) {
        print qq|\t\t<optgroup label="$subkey">\n|;
        foreach my $subsubkey( sort keys %{$time_zones{$key}{$subkey}} ) {
          print qq|\t\t\t<option 
value="$time_zones{$key}{$subkey}{$subsubkey}">$subsubkey</option>\n|;
        }
        print qq|\t\t</optgroup>\n|;
      } else {
        print qq|\t\t<option 
value="$time_zones{$key}{$subkey}">$subkey</option>\n|;
      }
    }
    print qq|\t</optgroup>\n|;
  } else {
    print qq|\t<option value="$time_zones{$key}">$key</option>\n|;
  }
}

The above code would allow you to feed it with a sub group of the 
data hash or the whole hash:
$select = make_select( %time_zones );
$select_usa = make_select( $time_zones{'North America'}{'United States'} );