Data::Visitor::Callback - phpMan

Data::Visitor::Callback(3pm)   User Contributed Perl Documentation   Data::Visitor::Callback(3pm)



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.

           These callbacks are called from least derived to most derived by comparing the
           classes' "isa" at construction time.

       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 AT 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.



perl v5.10.0                                2008-07-19               Data::Visitor::Callback(3pm)

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