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 Data::Visitor 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 Data::Visitor.

This is useful when you want to modify $_ directly

tied_as_objects

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

See "visit_tied" in Data::Visitor.

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 Data::Visitor 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.