dynamic hash name

priyankgandhi has asked for the wisdom of the Perl Monks concerning the following question:

my %citystate;
my %citycountry;
my %country;
my %airportCode;
my %geonameid;

if ($line =~ /.*Cannot find valid (destination) for type:(.*)=(.*)/) 
{
        my $type = $2;
        my $key = $3;
        if ($type =~ /citystate/) {
                $citystate{$key} = "";
        } elsif ($type =~ /citycountry/) {
                $citycountry{$key} = "";        
        } elsif ($type =~ /country/) {
                $country{$key} = "";
        } elsif ($type =~ /airportCode/) {
                $airportCode{$key} = "";
        } elsif ($type =~ /geonameid/) {
                $geonameid{$key} = "";
        }
}

for my $key ( keys %citystate ) {
                $fhdest -> print("<p>$key</p>");
        }
        for my $key ( keys %citycountry ) {
                $fhdest -> print("<p>$key</p>");
        }
        for my $key ( keys %airportCode ) {
                $fhdest -> print("<p>$key</p>");
        }
[download]

In the above code instead of using if-else conditions can I use something like $$type{$key} / $"$type"{$key} ?

Comment on dynamic hash name Download Code

Replies are listed 'Best First'.
Re: dynamic hash name by Tanktalus (Canon) on Feb 03, 2009 at 00:26 UTC
You can, but it involves symbolic references that you really shouldn't bother with until you know why. Instead, you need a symbol table of your own. Either: `my %destinations; if ($line =~ /.Cannot find valid (destination) for type:(.)=(.)/) { $destinations{$type}{$key} = ""; }` [download] or `my %citystate; my %citycountry; my %country; my %airportCode; my %geonameid; my %symboltable = ( citystate => \%citystate, citycountry => \%citycountry, country => \%country, airportCode => \%airportCode, geonameid => \%geonameid ); if ($line =~ /.Cannot find valid (destination) for type:(.)=(.)/) { $symboltable{$type}{$key} = "" }` [download] The first option is better. (Advanced monks may disagree, but for beginners, it simply is better. You can learn the second way when you really understand the first way and its limitations.)	[reply] [d/l] [select]
Re^2: dynamic hash name by priyankgandhi (Novice) on Feb 03, 2009 at 00:38 UTC
So for the first option: How do I iterate? Because at the end this is what I want to do. `for my $key ( keys %citystate ) { $fhdest -> print("<p>$key</p>"); } for my $key ( keys %citycountry ) { $fhdest -> print("<p>$key</p>"); } for my $key ( keys %airportCode ) { $fhdest -> print("<p>$key</p>"); }` [download]	[reply] [d/l]
Re^3: dynamic hash name by ikegami (Patriarch) on Feb 03, 2009 at 01:34 UTC
`$data{citystate}` contains a reference to a hash, so where you had `for my $key ( keys %citystate ) {` [download] you now use `for my $key ( keys %{ $data{citystate} } ) {` [download]	[reply] [d/l] [select]
Re: dynamic hash name by toolic (Bishop) on Feb 03, 2009 at 00:25 UTC
It would be cleaner to use a hash-of-hash-type data structure, something like: `my %data; ... if ($type =~ /citystate/) { $data{citystate}{$key}; } elsif ($type =~ /citycountry/) { $data{citycountry}{$key}; } elsif ($type =~ /country/) { $data{country}{$key}; ...` [download]	[reply] [d/l]