package ProcessData;
use strict;
no strict "refs";
use Carp qw(croak);

sub new {
    my ($pkg) = $_[0];
    bless {
        _dispatch_table => {},
    }, $pkg;
}

sub add_subroutine {
    if($_[1] && $_[2]) {
        if(ref($_[2]) eq "CODE") {
            ${$_[0]->{_dispatch_table}}{$_[1]} = $_[2];
        } else {
            croak "The reference passed to add_subroutine() is not a CODE reference. ";
        }
    } else {
        croak "Insufficient arguments passed to add_subroutine(). ";
    }
}

sub process_data {
    if($_[1] && $_[2]) {
        #I've tried:
        ${$_[0]->{_dispatch_table}}{$_[1]}->($_[2]);
        
        #and tried
        ${${$_[0]->{_dispatch_table}}{$_[1]}}->($_[2]);

        #and some pretty odd other comibnations
        
        ... do stuff with the data ...
    } else {
        croak "Insufficient arguments passed to process_data(). ";
    }
}

sub process_locations {
    $_[0]->process_data("locations");
}


test.pl
use strict;
use ProcessData;


my $pd = ProcessData->new();

#Add references to the dispatch table.
$pd->add_subroutine("dates", \&get_dates);
$pd->add_subroutine("locations" \&get_locations);
$pd->add_subroutine("contact_list", \&contact_list);

$pd->process_locations;