Class::ReturnValue(3p)

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:\n".
        $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:\n".
        $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 ($retval) {
                print "Yay. we did something\n";
                my ($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.

POD ERRORS
Hey! The above document had some coding errors, which are explained below:

Around line 97:
    '=item' outside of any '=over'

Around line 264:
    =cut found outside a pod block. Skipping to next block.

Around line 296:
    You forgot a '=back' before '=head1'