{
  package foo;
  sub add {
    my ($x, $y) = @_;
    die "not a number\n" unless $x =~ /\d/ and $y =~ /\d/;
    $x + $y
  }
}

# catch any exceptions
eval {
  print "1+2==", foo::add(1, 2);
  print "a+2==", foo::add("a", 2);
};

# handle any exceptions caught by eval
if ($@) {
  push @errors, $@;
}

# program continues...