NAME
    Acme::CPANModules::HashUtilities - Modules that manipulate hashes

VERSION
    This document describes version 0.002 of
    Acme::CPANModules::HashUtilities (from Perl distribution
    Acme-CPANModules-HashUtilities), released on 2020-03-01.

DESCRIPTION
    Modules that manipulate hashes.

    Most of the time, you don't need modules to manipulate hashes; Perl's
    built-in facilities suffice. The modules below, however, are sometimes
    convenient. This list is organized by task.

  Creating an alias to another variable
    Hash::Util's "hv_store" allows you to store an alias to a variable in a
    hash instead of copying the value. This means, if you set a hash value,
    it will instead set the value of the aliased variable instead. Copying
    from Hash::Util's documentation:

     my $sv = 0;
     hv_store(%hash,$key,$sv) or die "Failed to alias!";
     $hash{$key} = 1;
     print $sv; # prints 1

  Getting internal information
    Aside from creating restricted hash, Hash::Util also provides routines
    to get information about hash internals, e.g. "hash_seed()",
    "hash_value()", "bucket_info()", "bucket_stats()", etc.

  Merging
    Merging hashes is usually as simple as:

     my %merged = (%hash1, %hash2, %hash3);

    but sometimes you want different merging behavior, particularly in case
    where the same key is found in more than one hash. See the various hash
    merging modules:

    Hash::Merge

    Data::ModeMerge

    Hash::Union

  Providing default value for non-existing keys
    Hash::WithDefault

  Restricting keys
    Perl through Hash::Util (a core module) allows you to restrict what keys
    can be set in a hash. This can be used to protect against typos and for
    simple validation. (For more complex validation, e.g. allowing patterns
    of valid keys and/or rejecting patterns of invalid keys, you can use the
    tie mechanism.)

  Reversing (inverting)
    Reversing a hash (where keys become values and values become keys) can
    be done using the builtin's "reverse" (which actually just reverse a
    list):

     %hash = (a=>1, b=>2);
     %reverse = reverse %hash; # => (2=>"b", 1=>"a")

    Since the new keys can contain duplicates, this can "destroy" some old
    keys:

     %hash = (a=>1, b=>1);
     %reverse = reverse %hash; # => sometimes (1=>"b"), sometimes (1=>"a")

    Hash::MoreUtil's "safe_reverse" allows you to specify a coderef that can
    decide whether to ignore overwriting, croak, or whatever else.

  Slicing (creating subset)
    Hash::MoreUtils's "slice_*" functions.

    Hash::Subset

    Hash::Util::Pick

  Tying
    The tie mechanism, although relatively slow, allows you to create
    various kinds of "magical" hash that does things whenever you get or set
    keys.

INCLUDED MODULES
    *   Hash::Util

    *   Hash::Merge

    *   Data::ModeMerge

    *   Hash::Union

    *   Hash::WithDefault

    *   Hash::MoreUtil

    *   Hash::MoreUtils

    *   Hash::Subset

    *   Hash::Util::Pick

FAQ
  What are ways to use this module?
    Aside from reading it, you can install all the listed modules using
    cpanmodules:

        % cpanmodules ls-entries HashUtilities | cpanm -n

    or Acme::CM::Get:

        % perl -MAcme::CM::Get=HashUtilities -E'say $_->{module} for @{ $LIST->{entries} }' | cpanm -n

    This module also helps lcpan produce a more meaningful result for "lcpan
    related-mods" when it comes to finding related modules for the modules
    listed in this Acme::CPANModules module.

HOMEPAGE
    Please visit the project's homepage at
    <https://metacpan.org/release/Acme-CPANModules-HashUtilities>.

SOURCE
    Source repository is at
    <https://github.com/perlancar/perl-Acme-CPANModules-HashUtilities>.

BUGS
    Please report any bugs or feature requests on the bugtracker website
    <https://rt.cpan.org/Public/Dist/Display.html?Name=Acme-CPANModules-Hash
    Utilities>

    When submitting a bug or request, please include a test-file or a patch
    to an existing test-file that illustrates the bug or desired feature.

SEE ALSO
    Acme::CPANModules - about the Acme::CPANModules namespace

    cpanmodules - CLI tool to let you browse/view the lists

AUTHOR
    perlancar <perlancar@cpan.org>

COPYRIGHT AND LICENSE
    This software is copyright (c) 2020 by perlancar@cpan.org.

    This is free software; you can redistribute it and/or modify it under
    the same terms as the Perl 5 programming language system itself.

