/ 
Exception-NoException-0.02
River stage zero No dependents
/ Exception::NoException

NAME

Exception::NoException - An exception object that's always false.

VERSION

Version 0.02

SYNOPSIS

Throw non-exception exceptions when you're using die() for flow control and want $@ to appear to be false/empty.

use Exception::NoException;
eval {
  die Exception::NoException->new;
};
die $@ if $@;

This is most useful when using File::Find::find or similar callback-using functions. You can wrap your call in an eval and stop execution by throwing a non-error. When you look at $@ to see if there's a problem, you won't find any.

METHODS

Exception::NoException-new>

This method takes no arguments and returns a new Exception::NoException object. This object overloads all available operators. Whenever an overloaded function is used a false value is returned and $@ is cleared.

Exception::NoException-AUTOLOAD>
$obj-AUTOLOAD>

This uses autoload to always return &_false when called for any method.

$obj-_false>

Clears $@ and returns a false value.

EXAMPLES

File::Find::find
use File::Find;
use Exception::NoException;

eval {
    find( sub {
        if ( $File::Find::name =~ /something/ ) {
            # do something with the file
            die Exception::NoException->new;
        }
    } );
};
die $@ if $@;

CAVEATS

ref() and blessed() will still return true for these objects. I'm considering using the 0 and/or \0 packages for this.

AUTHOR

Joshua ben Jore, <jjore at cpan.org>

BUGS

Please report any bugs or feature requests to bug-exception-noexception at rt.cpan.org, or through the web interface at http://rt.cpan.org/NoAuth/ReportBug.html?Queue=Exception-NoException. I will be notified, and then you'll automatically be notified of progress on your bug as I make changes.

SUPPORT

You can find documentation for this module with the perldoc command.

perldoc Exception::NoException

You can also look for information at:

ACKNOWLEDGEMENTS

Yitzchak Scott-Thoennes came up with a problem where an exception object used an eval block during the bool conversion from overload. The following snippet caused him hours of grief and it inspired me to come up with an object where that effect was actually desired. It also happens to solve a common problem with loops that use callbacks.

# Yitzchak's problem:
eval {
    die SomeObject->new;
};
if ( $@ ) {
    # now $@ is empty.
}
package SomeObject;
use overload bool => sub { eval { } };
sub new { bless [], shift }

To solve Yitzchak's problem, copy $@ ala my $e = $@ before examining it.

COPYRIGHT & LICENSE

Copyright 2006 Joshua ben Jore, all rights reserved.

This program is free software; you can redistribute it and/or modify it under the same terms as Perl itself.