/ 
Data-Dmap-0.04
River stage one • 1 direct dependent • 1 total dependent
/ Data::Dmap

NAME

Data::Dmap - just like map, but on deep data structures

VERSION

Version 0.04

SYNOPSIS

This module provides the single function dmap which carries out a map-like operation on deep data structures.

use Data::Dmap;

my $foo = {
    cars => [ 'ford', 'opel', 'BMW' ],
    birds => [ 'cuckatoo', 'ostrich', 'frigate' ],
    handler => sub { print "barf\n" }
};

# This removes all keys named 'cars'    
my($bar) = dmap { delete $_->{cars} if ref eq 'HASH'; $_ } $foo;

# This replaces arrays with the number of elements they contains
my($other) = dmap { $_ = scalar @$_ if ref eq 'ARRAY'; $_ } $foo;

use Data::Dumper;
print Dumper $other;
#
# Prints
# {
#    birds => 3,
#    handler => sub { "DUMMY" }
# }
# (Data::Dumper doesn't dump subs)

$other->{handler}->();
# Prints
# barf

EXPORT

dmap - the dmap function that does deep in-place mapping

SUBROUTINES/METHODS

dmap

This function works like map - it takes an expression followed by a list, evaluates the expression on each member of the list and returns the result.

The only difference is that any references returned by the expression will also be traversed and passed to the expression once again, thus making it possible to make deep traversal of any data structure.

Objects (references blessed to something) are just traversed as if they weren't blessed.

Examples

Delete all hash references

use Data::Dmap;
use Data::Dump 'pp';

pp dmap { return $_ unless ref eq 'HASH'; return; } 1, 'foo', [ { a => 1 }, 2];

# Prints:
# (1, "foo", [2])

Delete every odd number

use Data::Dmap;
use Data::Dump 'pp';

pp dmap { return if $_ % 2; $_ } [ 1 .. 10 ];

# Prints:
# [2, 4, 6, 8, 10]

Replace all hash refs with some $object of class thingy.

use Data::Dmap;
use Data::Dump 'pp';

pp dmap { return bless $_, 'thingy' if ref eq 'HASH'; $_ } [ 1, "hello", { a => 1 } ];

Because the output from the expression is being traversed, you can use dmap to generate data structures:

use Data::Dmap;
use Data::Dump 'pp';

my $height = 3;
pp dmap { if(ref eq 'HASH' and $height--) { $_->{a} = {height => $height} } $_ } {};

# Prints:
# {
#     a => {
#         a => {
#             a => { 
#                 height => 0
#             },
#             height => 1
#         },
#         height => 2
#     }
# }
# (My own formatting above.)

AUTHOR

Michael Zedeler, <michael@zedeler.dk>

BUGS

If you find a bug, please consider helping to fix the bug by doing this:

  • Fork Data::Dmap from http://github.com/mzedeler/Data-Dmap

  • Write a test case in the t directory, commit and push it.

  • Fix the bug or (if you don't know how to fix it), report the bug

Bugs and feature requests can be reported through the web interface at http://github.com/mzedeler/Data-Dmap/issues. I may not be notified, so send me a mail too.

SUPPORT

You can find documentation for this module with the perldoc command.

perldoc Data::Dmap

You can also look for information at:

ACKNOWLEDGEMENTS

LICENSE AND COPYRIGHT

Copyright 2010 Michael Zedeler.

This program is free software; you can redistribute it and/or modify it under the terms of either: the GNU General Public License as published by the Free Software Foundation; or the Artistic License.

See http://dev.perl.org/licenses/ for more information.