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Man Pages


Manual Reference Pages  -  HASH::MOREUTILS (3)

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NAME

Hash::MoreUtils - Provide the stuff missing in Hash::Util

CONTENTS

SYNOPSIS



  use Hash::MoreUtils qw(slice slice_def slice_exists slice_grep
                         hashsort
                        );



DESCRIPTION

Similar to List::MoreUtils, Hash::MoreUtils contains trivial but commonly-used functionality for hashes.

FUNCTIONS

CWslice HASHREF[, LIST]

Returns a hash containing the (key, value) pair for every key in LIST.

If no LIST is given, all keys are assumed as LIST.

CWslice_def HASHREF[, LIST]

As slice, but only includes keys whose values are defined.

If no LIST is given, all keys are assumed as LIST.

CWslice_exists HASHREF[, LIST]

As slice but only includes keys which exist in the hashref.

If no LIST is given, all keys are assumed as LIST.

CWslice_grep BLOCK, HASHREF[, LIST]

As slice, with an arbitrary condition.

If no LIST is given, all keys are assumed as LIST.

Unlike grep, the condition is not given aliases to elements of anything. Instead, %_ is set to the contents of the hashref, to avoid accidentally auto-vivifying when checking keys or values. Also, ’uninitialized’ warnings are turned off in the enclosing scope.

CWslice_map HASHREF[, MAP]

Returns a hash containing the (key, value) pair for every key in MAP.

If no MAP is given, all keys of HASHREF are assumed mapped to theirself.

CWslice_def_map HASHREF[, MAP]

As slice_map, but only includes keys whose values are defined.

If no MAP is given, all keys of HASHREF are assumed mapped to theirself.

CWslice_exists_map HASHREF[, MAP]

As slice_map but only includes keys which exist in the hashref.

If no MAP is given, all keys of HASHREF are assumed mapped to theirself.

CWslice_grep_map BLOCK, HASHREF[, MAP]

As slice_map, with an arbitrary condition.

If no MAP is given, all keys of HASHREF are assumed mapped to theirself.

Unlike grep, the condition is not given aliases to elements of anything. Instead, %_ is set to the contents of the hashref, to avoid accidentally auto-vivifying when checking keys or values. Also, ’uninitialized’ warnings are turned off in the enclosing scope.

CWhashsort [BLOCK,] HASHREF



  my @array_of_pairs  = hashsort \%hash;
  my @pairs_by_length = hashsort sub { length($a) <=> length($b) }, \%hash;



Returns the (key, value) pairs of the hash, sorted by some property of the keys. By default (if no sort block given), sorts the keys with cmp.

I’m not convinced this is useful yet. If you can think of some way it could be more so, please let me know.

CWsafe_reverse [BLOCK,] HASHREF



  my %dup_rev = safe_reverse \%hash

  sub croak_dup {
      my ($k, $v, $r) = @_;
      exists( $r->{$v} ) and
        croak "Cannot safe reverse: $v would be mapped to both $k and $r->{$v}";
      $v;
  };
  my %easy_rev = save_reverse \&croak_dup, \%hash



Returns safely reversed hash (value, key pairs of original hash). If no BLOCK is given, following routine will be used:



  sub merge_dup {
      my ($k, $v, $r) = @_;
      return exists( $r->{$v} )
             ? ( ref($r->{$v}) ? [ @{$r->{$v}}, $k ] : [ $r->{$v}, $k ] )
             : $k;
  };



The BLOCK will be called with 3 arguments:
key The key from the ( key, value ) pair in the original hash
value The value from the ( key, value ) pair in the original hash
ref-hash Reference to the reversed hash (read-only)
The BLOCK is expected to return the value which will used for the resulting hash.

AUTHOR

Hans Dieter Pearcey, <hdp@cpan.org>, Jens Rehsack, <rehsack@cpan.org>

BUGS

Please report any bugs or feature requests to bug-hash-moreutils@rt.cpan.org, or through the web interface at <http://rt.cpan.org/NoAuth/ReportBug.html?Queue=Hash-MoreUtils>. I will be notified, and then you’ll automatically be notified of progress on your bug as I make changes.

SUPPORT

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



    perldoc Hash::MoreUtils



You can also look for information at:
o RT: CPAN’s request tracker

<http://rt.cpan.org/NoAuth/Bugs.html?Dist=Hash-MoreUtils>

o AnnoCPAN: Annotated CPAN documentation

<http://annocpan.org/dist/Hash-MoreUtils>

o CPAN Ratings

<http://cpanratings.perl.org/d/Hash-MoreUtils>

o Search CPAN

<http://search.cpan.org/dist/Hash-MoreUtils/>

ACKNOWLEDGEMENTS

COPYRIGHT & LICENSE

Copyright 2005 Hans Dieter Pearcey, all rights reserved. Copyright 2010-2013 Jens Rehsack

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.

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perl v5.20.3 HASH::MOREUTILS (3) 2016-03-17

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