use Carp;

# Takes an anon hash of args, an anon array of required fields,
# an optional anon array of optional args, and an optional
# anon hash of defaults.  Returns an array of the determined
# values
sub proc_args {
  my $args = shift;
  my $req = shift;
  my $opt = shift || [];
  my $default = shift || {};
  my @res;
  foreach my $arg (@$req) {
    if (exists $args->{$arg}) {
      push @res, $args->{$arg};
      delete $args->{$arg};
    }
    else {
      confess("Missing required argument $arg");
    }
  }
  foreach my $arg (@$opt) {
    if (exists $args->{$arg}) {
      push @res, $args->{$arg};
      delete $args->{$arg};
    }
    else {
      push @res, $default->{$arg};
    }
  }
  if (%$args) {
    my $bad = join ", ", sort keys %$args;
    confess("Unrecognized arguments: $bad\n");
  }
  else {
    return @res;
  }
}