Concurrent::Errorhandler - Error handling mechanism for Concurrent.
package Foo;
use Concurrent::Errorhandler;
@ISA = qw(Concurrent::Errorhandler);
sub alive {
..
..
return
$self->error ("Awake, awake! Ring the alarum bell. \
Murther and treason!", $dagger)
if $self->murdered($king);
}
package main;
use Foo;
my $foo = new Foo;
$foo->alive($king) or print $foo->errstr();
# prints "Awake, awake! ... "
Concurrent::Errorhandler encapsulates the error handling mechanism used by the modules in Concurrent bundle. Concurrent::Errorhandler doesn't have a constructor and is meant to be inherited. The derived modules use its two methods, error() and errstr(), to communicate error messages to the caller.
When a method of the derived module fails, it calls $self->error() and returns undef to the caller. The error message passed to error() is made available to the caller through the errstr() accessor. error() also accepts a list of sensitive data that it wipes out (undef'es) before returning.
The caller should never call errstr() to check for errors. errstr() should be called only when a method indicates (usually through an undef return value) that an error has occured. This is because errstr() is never overwritten and will always contain a value after the occurance of first error.
The first argument to error() is $message which is placed in $self->{errstr} and the remaining arguments are interpretted as variables containing sensitive data that are wiped out from the memory. error() always returns undef.
errstr() is an accessor method for $self->{errstr}.
Vipul Ved Prakash, <mail@vipul.net>
Concurrent(3)
