Please enlighten me.... I'd like to detect overflow during integer operations. Using the integer pragma guarantees that Perl does not converts integers to reals, but it doesn't detect overflow...

I'm trying to write a Perl module to do arithmetic on arbitrary precision integers. Obviously, these new operation will pay an overload on built-in operators for these cases in which the latter can be used. So I'd like to use standard built-in whenever possible. I tried to do something like

sub add {
  use integers;
  my $result = eval {$_[0] + $_[1]};
  return $result if (defined $result);
  goto &myadd;
}
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where myadd is the subroutine handling the case where one at least is a "big" integer.. Well, it didn't work :( Even with the inter pragma, overflow errors aren't detected... Any idea?