Select Code to Download

$$database_handle = DBI->connect(
                     map {
...
                        taint)
                ) or die "Could not connect to the ".
                         "database: $DBI::errstr";

sub database_username {
    return "fred";
}

my %defaults = (
      data_source_name => ".....",
...
                                 username password taint) }) 
          or die "Could not connect to the database: ".
                 "$DBI::errstr";

my %defaults = (
        data_source_name => \&database_data_source_name,
...
       # do other stuff
       return #something
}

           map {
                   exists $arguments{$_} ?
                   $arguments{$_}  :
                   ${\"database_$_"}->()
           }