package Err.pm

sub err {
    my %args = (
        title =>'Really Bad Error',
        msg => undef,
       @_ 
   );
   # do something with %args here.
}

###########
package MyModule.pm;
use Err.pm;

sub err {
  my %args = (
        title =>'My new default title for MyModule.pm',
        msg => 'MyModules generic error message',
       @_ 
   );
   return Err::err(%args);
}

##################
### my script.cgi

package MyModule;

do_the_right_thing() || err(title=>'Oops',msg=>'something went wrong');