NAME

       Lexical::Failure::Objects - Special failure objects for Lexical::Failure

VERSION

       This document describes Lexical::Failure::Objects version 0.000001

DESCRIPTION

       This module implements the "failure objects" returned by the optional 'failobj' mechanism
       of the "Lexical::Failure" module.

       When "ON_FAILURE 'failobj'" is in effect, any call to "fail" will return one of these
       objects, which simulates a special out-of-band value that you can either explicitly test
       for failure or else simply ignore and automatically get an exception.

       For example, given the subroutine:

           package Math;
           use Lexical::Failure;

           sub inverse_square {
               my ($n) = @_;

               if ($n == 0) {
                   fail "Can't invert zero";
               }

               return 1/$n**2;
           }

       when 'failobj' is the selected failure signalling strategy:

           use Math (fail => 'failobj')

       then failure can either be tested for explicitly:

           # This block skipped if $n == 0...
           if (my $inv_sq = Math::inverse_square($n) {
               print $inv_sq;
           }

       or else simply ignored, in which case an exception will automatically be thrown:

           print inverse_square($n);    # ...throw exception if $n == 0

INTERFACE

       If it is used as a boolean, a failure object evaluates false (i.e. it acts as if
       "ON_FAILURE 'undef'" had been in effect).

       If it is used as a value in any other way (as a string, as a reference, as a regex, as a
       filehandle, etc., etc.), or if it's ignored and allowed to go out of scope without being
       evaluated at all, then a failure object throws an exception (i.e. it acts as if
       "ON_FAILURE 'croak'" had been in effect).

   Constructor ("new()")
       The class's constructor expects two named arguments:

           $failure_obj = Lexical::Failure::Objects->new(
                              msg     => $MESSAGE_STR_OR_OBJ,
                              context => [$PACKAGE, $FILE, $LINE, $SUBNAME],
                          );

       You should never normally need to construct failure objects directly; it's better to let
       "Lexical::Failure" craete them automatically via its 'failobj' mechanism.

   Methods
       "Lexical::Failure::Objects" also provides four methods with which you can query the
       location of the failure that they represent. None of these methods takes any arguments.

       "$failobj->subname()"
           Returns the name of the subroutine in which the failure was signaled.  That is, the
           equivalent of "(caller 0)[3]".

       "$failobj->file()"
           Returns the name of the file containing the subroutine call from which failure was
           signaled.  That is, the equivalent of "(caller 0)[1]".

       "$failobj->line()"
           Returns the line number of the subroutine call from which failure was signaled.  That
           is, the equivalent of "(caller 0)[2]".

       "$failobj->context()"
           Returns a string summarizing the information provided by the previous three methods,
           in the form:

               "call to <subname> at <file> line <line>"

DIAGNOSTICS

       None of their own.

       If they throw an exception (when misused or ignored), it will be the exception that "fail"
       would otherwise have thrown.

CONFIGURATION AND ENVIRONMENT

       Lexical::Failure::Objects requires no configuration files or environment variables.

DEPENDENCIES

       Requires the Hash::Util::FieldHash module.

INCOMPATIBILITIES

       None reported.

BUGS AND LIMITATIONS

       No bugs have been reported.

       Please report any bugs or feature requests to "bug-lexical-failure@rt.cpan.org", or
       through the web interface at <http://rt.cpan.org>.

AUTHOR

       Damian Conway  "<DCONWAY@cpan.org>"

LICENCE AND COPYRIGHT

       Copyright (c) 2013, Damian Conway "<DCONWAY@cpan.org>". All rights reserved.

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

DISCLAIMER OF WARRANTY

       BECAUSE THIS SOFTWARE IS LICENSED FREE OF CHARGE, THERE IS NO WARRANTY FOR THE SOFTWARE,
       TO THE EXTENT PERMITTED BY APPLICABLE LAW. EXCEPT WHEN OTHERWISE STATED IN WRITING THE
       COPYRIGHT HOLDERS AND/OR OTHER PARTIES PROVIDE THE SOFTWARE "AS IS" WITHOUT WARRANTY OF
       ANY KIND, EITHER EXPRESSED OR IMPLIED, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
       WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE. THE ENTIRE RISK AS TO
       THE QUALITY AND PERFORMANCE OF THE SOFTWARE IS WITH YOU. SHOULD THE SOFTWARE PROVE
       DEFECTIVE, YOU ASSUME THE COST OF ALL NECESSARY SERVICING, REPAIR, OR CORRECTION.

       IN NO EVENT UNLESS REQUIRED BY APPLICABLE LAW OR AGREED TO IN WRITING WILL ANY COPYRIGHT
       HOLDER, OR ANY OTHER PARTY WHO MAY MODIFY AND/OR REDISTRIBUTE THE SOFTWARE AS PERMITTED BY
       THE ABOVE LICENCE, BE LIABLE TO YOU FOR DAMAGES, INCLUDING ANY GENERAL, SPECIAL,
       INCIDENTAL, OR CONSEQUENTIAL DAMAGES ARISING OUT OF THE USE OR INABILITY TO USE THE
       SOFTWARE (INCLUDING BUT NOT LIMITED TO LOSS OF DATA OR DATA BEING RENDERED INACCURATE OR
       LOSSES SUSTAINED BY YOU OR THIRD PARTIES OR A FAILURE OF THE SOFTWARE TO OPERATE WITH ANY
       OTHER SOFTWARE), EVEN IF SUCH HOLDER OR OTHER PARTY HAS BEEN ADVISED OF THE POSSIBILITY OF
       SUCH DAMAGES.