Data::Visitor::Callback - A Data::Visitor with callbacks.

NAME

Data::Visitor::Callback - A Data::Visitor with callbacks.

SYNOPSIS

        use Data::Visitor::Callback;
        my $v = Data::Visitor::Callback->new(
                value => sub { ... },
                array => sub { ... },
        );
        $v->visit( $some_perl_value );

DESCRIPTION

This is a the Data::Visitor manpage subclass that lets you invoke callbacks instead of needing to subclass yourself.

METHODS

new %opts, %callbacks
Construct a new visitor.

The options supported are:

ignore_return_values
When this is true (off by default) the return values from the callbacks are ignored, thus disabling the fmapping behavior as documented in the Data::Visitor manpage.

This is useful when you want to modify $_ directly

tied_as_objects
Whether ot not to visit the tied in the perlfunc manpage of a tied structure instead of pretending the structure is just a normal one.

See visit_tied in the Data::Visitor manpage.

CALLBACKS

Use these keys for the corresponding callbacks.

The callback is in the form:

        sub {
                my ( $visitor, $data ) = @_;
                # or you can use $_, it's aliased
                return $data; # or modified data
        }

Within the callback $_ is aliased to the data, and this is also passed in the parameter list.

Any method can also be used as a callback:

        object => "visit_ref", # visit objects anyway
visit
Called for all values

value
Called for non objects, non container (hash, array, glob or scalar ref) values.

ref_value
Called after value, for references to regexes, globs and code.

plain_value
Called after value for non references.

object
Called for blessed objects.

Since visit_object in the Data::Visitor manpage will not recurse downwards unless you delegate to visit_ref, you can specify visit_ref as the callback for object in order to enter objects.

It is reccomended that you specify the classes (or base classes) you want though, instead of just visiting any object forcefully.

Some::Class
You can use any class name as a callback. This is colled only after the object callback.

If the object isa the class then the callback will fire.

object_no_class
Called for every object that did not have a class callback.

object_final
The last callback called for objects, useful if you want to post process the output of any class callbacks.

array
Called for array references.

hash
Called for hash references.

glob
Called for glob references.

scalar
Called for scalar references.

tied
Called on the return value of tied for all tied containers. Also passes in the variable as the second argument.

AUTHOR

Yuval Kogman <nothingmuch@woobling.org>

COPYRIGHT & LICENSE

        Copyright (c) 2006 Yuval Kogman. All rights reserved
        This program is free software; you can redistribute
        it and/or modify it under the same terms as Perl itself.
 Data::Visitor::Callback - A Data::Visitor with callbacks.