use Carp;

my %allowed_keys;
my %allowed_values;

sub function {
    my ( $arrayref, $hashref ) = @_;
    croak 'First Argument has to be an Arrayref' if !defined $arrayref or ref $arrayref ne 'ARRAY';

    my %hash=( ... ); # vordefiniert
    if ( defined $hashref ) {
        croak 'Second Argument has to be an Hashref' if ref $hashref ne 'HASH'
        # test keys und values
        my @not_allowed_keys=grep{ !$allowed_keys{$_} }keys(%$hashref);
        my @not_allowed_vals=grep{ !$allowed_values{$_} }values(%$hashref);
        carp 'Ignoring Keys :'.join( ', ', @not_allowed_keys ) if @not_allowed_keys;
        carp 'Ignoring Values :'.join( ', ', @not_allowed_vals ) if @not_allowed_values;

        %hash=map { $_ => $hashref->{$_} }
              grep{ $allowed_values{ $hashref->{$_} } }
              grep{ $allowed_keys{$_} }
              keys %$hashref ;
    }

    my @return;

    ...
    ...
    
    return @return;
}