1Data::Visitor::CallbackU(s3e)r Contributed Perl DocumentaDtaitoan::Visitor::Callback(3)
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NAME

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

9               use Data::Visitor::Callback;
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11               my $v = Data::Visitor::Callback->new(
12                       value => sub { ... },
13                       array => sub { ... },
14               );
15
16               $v->visit( $some_perl_value );
17

DESCRIPTION

19       This is a Data::Visitor subclass that lets you invoke callbacks instead
20       of needing to subclass yourself.
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METHODS

23       new %opts, %callbacks
24           Construct a new visitor.
25
26           The options supported are:
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28           ignore_return_values
29               When this is true (off by default) the return values from the
30               callbacks are ignored, thus disabling the fmapping behavior as
31               documented in Data::Visitor.
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33               This is useful when you want to modify $_ directly
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CALLBACKS

36       Use these keys for the corresponding callbacks.
37
38       The callback is in the form:
39
40               sub {
41                       my ( $visitor, $data ) = @_;
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43                       # or you can use $_, it's aliased
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45                       return $data; # or modified data
46               }
47
48       Within the callback $_ is aliased to the data, and this is also passed
49       in the parameter list.
50
51       Any method can also be used as a callback:
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53               object => "visit_ref", # visit objects anyway
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55       visit
56           Called for all values
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58       value
59           Called for non objects, non container (hash, array, glob or scalar
60           ref) values.
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62       ref_value
63           Called after "value", for references to regexes, globs and code.
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65       plain_value
66           Called after "value" for non references.
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68       object
69           Called for blessed objects.
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71           Since "visit_object" in Data::Visitor will not recurse downwards
72           unless you delegate to "visit_ref", you can specify "visit_ref" as
73           the callback for "object" in order to enter objects.
74
75           It is reccomended that you specify the classes you want though,
76           instead of just visiting any object forcefully.
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78       Some::Class
79           You can use any class name as a callback. This is clled only after
80           the "object" callback.
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82       array
83           Called for array references.
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85       hash
86           Called for hash references.
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88       glob
89           Called for glob references.
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91       scalar
92           Called for scalar references.
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AUTHOR

95       Yuval Kogman <nothingmuch@woobling.org>
96

98               Copyright (c) 2006 Yuval Kogman. All rights reserved
99               This program is free software; you can redistribute
100               it and/or modify it under the same terms as Perl itself.
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104perl v5.8.8                       2007-10-07        Data::Visitor::Callback(3)
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