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I have a server written in Perl that does some tasks that clients ask it to. Requests and responses are passed using soap, namely SOAP::Lite. Responses can be successful or unsuccessful. The latter are of two types: error codes plus honest-to-God exceptions (well, as close as Perl comes to them, anyway) of type Error or Exception::Class. The problem occurs when SOAP::Serializer tries to serialize objects of type Error. Error.pm has the following code (shortened for our purposes):
use overload ("0+" => 'value'); sub value { my $self = shift; exists $self->{'-value'} ? $self->{'-value'} : undef; }
Note that this subroutine may return undef. Now, SOAP::Serializer calls subroutine gen_id on references, which for normal objects is just the value of memory address:
sub gen_id { sprintf "%U", $_[1] }
Now, the problem is that when objects of type Error do not have a value (returns undef), this produces a segfault in perl 5.6.1. This problem can be demonstrated with the following short script:
package My; use overload ('0+' => 'num_conv'); sub new { my $self = shift; bless {}, ref($self) || $self; } sub num_conv { undef } package main; my $var = My->new; print int($var);
We see that when numeric conversion overloading function returns undef to built-in Perl functions that invoke it, that crashes perl. My question is, how do I approach this problem? Do I try to
  • find out whether I can modify Error.pm (drop numeric conversion overload insanity) and figuring out the implications of such change;
  • modify gen_id routine to turn off numeric conversion overloading for referenced packages that are passed to it;
  • other?
Your input is greatly appreciated. Thank you.

In reply to When numeric conversion overloading goes awry. by dmitri

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