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Man Pages


Manual Reference Pages  -  HASH::UNION (3)

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NAME

Hash::Union - smart hashes merging

CONTENTS

VERSION

Version 0.03

SYNOPSIS



  use Hash::Union union;
  use Data::Dumper;                # for debug only

  my $config_base = {              # default application config
      database => production,  # production database
      html_dirs => [             # search paths for html documents
          /docs/html/main,
          /docs/html/default
      ],
      text_dirs => [             # search paths fo text documents
          /docs/text/main,
          /docs/text/default
      ]
  };

  my $config_local = {             # locally customized config
      database => stageing,    # devel database
      prepend: html_dirs => [    # local html pages preferred
          /local/html/main,
          /local/html/default
      ],
      append: text_dirs => [     # fallback for nonexistent text
          /local/text/main,
          /local/text/default
      ]
  };

  # now merge default with local
  my $config = union( [ $config_base, $config_local ] );

  print Dumper $config;

  ========

  $VAR1 = {
      database => stageing,
      html_dirs => [
          /local/html/main,
          /local/html/default,
          /docs/html/main,
          /docs/html/default
      ],
      text_dirs => [
          /docs/text/main,
          /docs/text/default,
          /local/text/main,
          /local/text/default
      ]
  };



EXPORT_OK

union( \@hash_references, CW%options );

Supported options:
o reverse

Merge all hash references in reverse order.

o simple

Don’t apply complex merging logic (ignore keys special meaning).

KEYS SPECIAL MEANING

Setting new value unconditionally: Key syntax: ’=KEY’, ’= KEY’, ’set:KEY’, ’set: KEY

Previous value of KEY will be lost and new value will be set unconditionally. This kind of merging logic applies to any ’plain’ keys by default. Passed option ’simple’ forces this method for ’complex’ keys too.

Setting new value only if no true value still exists: Key syntax: ’?=KEY’, ’?= KEY’ , ’ifnone:KEY’, ’ifnone: KEY

If true (from perl point of view) value for this key exists just skip new value assignment. Otherwise assign new value (possible even false).

Prepending new value to existing: Key syntax: ’+=KEY’, ’+= KEY’, ’prepend:KEY’, ’prepend: KEY

Prepend new value to any existing value of key. Raise an exception on an incompatible value types. Scalars will be concatenated, arrays unshifted, hashes traversed deeply in proper order.

Appending new value to existing: Key syntax: ’=+KEY’, ’=+ KEY’, ’append:KEY’, ’append: KEY

Append new value to any existing value of key. Raise an exception on an incompatible value types. Scalars will be concatenated, arrays pushed, hashes traversed deeply in proper order.

<B>NOTEB>: In all syntax forms spaces between operation and key are optional.

AUTHOR

Oleg A. Mamontov, <oleg at mamontov.net>

BUGS

Please report any bugs or feature requests to bug-hash-union at rt.cpan.org, or through the web interface at <http://rt.cpan.org/NoAuth/ReportBug.html?Queue=Hash-Union>. 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::Union



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

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

o AnnoCPAN: Annotated CPAN documentation

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

o CPAN Ratings

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

o Search CPAN

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

COPYRIGHT & LICENSE

Copyright 2009 Oleg A. Mamontov, all rights reserved.

This program is free software; you can redistribute it and/or modify it under the same terms as Perl itself.

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perl v5.20.3 HASH::UNION (3) 2009-02-11

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