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class::returnvalue(3pm) [debian man page]

Class::ReturnValue(3pm) 				User Contributed Perl Documentation				   Class::ReturnValue(3pm)

NAME
Class::ReturnValue - A return-value object that lets you treat it as as a boolean, array or object DESCRIPTION
Class::ReturnValue is a "clever" return value object that can allow code calling your routine to expect: a boolean value (did it fail) or a list (what are the return values) EXAMPLE
sub demo { my $value = shift; my $ret = Class::ReturnValue->new(); $ret->as_array('0', 'No results found'); unless($value) { $ret->as_error(errno => '1', message => "You didn't supply a parameter.", do_backtrace => 1); } return($ret->return_value); } if (demo('foo')){ print "the routine succeeded with one parameter"; } if (demo()) { print "The routine succeeded with 0 paramters. shouldn't happen"; } else { print "The routine failed with 0 parameters (as it should)."; } my $return = demo(); if ($return) { print "The routine succeeded with 0 paramters. shouldn't happen"; } else { print "The routine failed with 0 parameters (as it should). ". "Stack trace: ". $return->backtrace; } my @return3 = demo('foo'); print "The routine got ".join(',',@return3). "when asking for demo's results as an array"; my $return2 = demo('foo'); unless ($return2) { print "The routine failed with a parameter. shouldn't happen.". "Stack trace: ". $return2->backtrace; } my @return2_array = @{$return2}; # TODO: does this work my @return2_array2 = $return2->as_array; METHODS
new Instantiate a new Class::ReturnValue object as_array Return the 'as_array' attribute of this object as an array. as_array [ARRAY] If $self is called in an array context, returns the array specified in ARRAY as_error HASH Turns this return-value object into an error return object. TAkes three parameters: message do_backtrace errno 'message' is a human readable error message explaining what's going on 'do_backtrace' is a boolean. If it's true, a carp-style backtrace will be stored in $self->{'backtrace'}. It defaults to true errno and message default to undef. errno _must_ be specified. It's a numeric error number. Any true integer value will cause the object to evaluate to false in a scalar context. At first, this may look a bit counterintuitive, but it means that you can have error codes and still allow simple use of your functions in a style like this: if ($obj->do_something) { print "Yay! it worked"; } else { print "Sorry. there's been an error."; } as well as more complex use like this: my $retval = $obj->do_something; if ($retval) { print "Yay. we did something "; my ($foo, $bar, $baz) = @{$retval}; my $human_readable_return = $retval; } else { if ($retval->errno == 20) { die "Failed with error 20 (Not enough monkeys)."; } else { die $retval->backtrace; # Die and print out a backtrace } } errno Returns the errno if there's been an error. Otherwise, return undef error_message If there's been an error return the error message. backtrace If there's been an error and we asked for a backtrace, return the backtrace. Otherwise, return undef. error_condition If there's been an error, return undef. Otherwise return 1 AUTHOR
Jesse Vincent <jesse@bestpractical.com> BUGS
This module has, as yet, not been used in production code. I thing it should work, but have never benchmarked it. I have not yet used it extensively, though I do plan to in the not-too-distant future. If you have questions or comments, please write me. If you need to report a bug, please send mail to <bug-class-returnvalue@rt.cpan.org> or report your error on the web at http://rt.cpan.org/ COPYRIGHT
Copyright (c) 2002,2003,2005,2007 Jesse Vincent <jesse@bestpractical.com> You may use, modify, fold, spindle or mutilate this module under the same terms as perl itself. SEE ALSO
Class::ReturnValue isn't an exception handler. If it doesn't do what you want, you might want look at one of the exception handlers below: Error, Exception, Exceptions, Exceptions::Class You might also want to look at Contextual::Return, another implementation of the same concept as this module. perl v5.8.8 2007-08-29 Class::ReturnValue(3pm)
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