$params = {
  from => ...,
  to => ...,
  # override the timeout of the system-wide config
  timeout => ...,
  # this is the config read from file
  config => {
    verbosity => 3,
    logger => ...,
    timeout => 5,
    ...
  }
};
sub distance {
  my $params = shift;
  # the timeout value will be the config's unless
  # caller passed their own value to temporarily override it
  my $timeout = exists($params->{timeout})
    ? $params->{timeout}
    : $params->{config}->{timeout}
  ;
  ...
  # similarly, I return back multiple values in a hash(ref)
  return {
   errormsg => 'nothing',
   status => 1, # all OK!
   distance => 42
  };
}
# call it
my $ret = distance($params);
die $ret->{errormsg} unless $ret->{status} == 1;