Hash::Merge::Simple - Recursively merge two or more hashes, simply

version 0.051

    use Hash::Merge::Simple qw/ merge /;

    my $a = { a => 1 };
    my $b = { a => 100, b => 2};

    # Merge with righthand hash taking precedence
    my $c = merge $a, $b;
    # $c is { a => 100, b => 2 } ... Note: a => 100 has overridden => 1

    # Also, merge will take care to recursively merge any subordinate hashes found
    my $a = { a => 1, c => 3, d => { i => 2 }, r => {} };
    my $b = { b => 2, a => 100, d => { l => 4 } };
    my $c = merge $a, $b;
    # $c is { a => 100, b => 2, c => 3, d => { i => 2, l => 4 }, r => {} }

    # You can also merge more than two hashes at the same time 
    # The precedence increases from left to right (the rightmost has the most precedence)
    my $everything = merge $this, $that, $mine, $yours, $kitchen_sink, ...;

Hash::Merge::Simple will recursively merge two or more hashes and return the result as a new hash reference. The merge function will descend and merge hashes that exist under the same node in both the left and right hash, but doesn't attempt to combine arrays, objects, scalars, or anything else. The rightmost hash also takes precedence, replacing whatever was in the left hash if a conflict occurs.

This code was pretty much taken straight from Catalyst::Utils, and modified to handle more than 2 hashes at the same time.

Merge <hash1> through <hashN>, with the nth-most (rightmost) hash taking precedence.

Returns a new hash reference representing the merge.

NOTE: The code does not currently check for cycles, so infinite loops are possible:

    my $a = {};
    $a->{b} = $a;
    merge $a, $a;

NOTE: If you want to avoid giving/receiving side effects with the merged result, use clone_merge or dclone_merge An example of this problem (thanks Uri):

    my $left = { a => { b => 2 } } ;
    my $right = { c => 4 } ;

    my $result = merge( $left, $right ) ;

    $left->{a}{b} = 3 ;
    $left->{a}{d} = 5 ;

    # $result->{a}{b} == 3 !
    # $result->{a}{d} == 5 !

Perform a merge, clone the merge, and return the result

This is useful in cases where you need to ensure that the result can be tweaked without fear of giving/receiving any side effects

This method will use Clone to do the cloning

Perform a merge, clone the merge, and return the result

This is useful in cases where you need to ensure that the result can be tweaked without fear of giving/receiving any side effects

This method will use Storable (dclone) to do the cloning

Hash::Merge

Catalyst::Utils

Clone

Storable

This code was pretty much taken directly from Catalyst::Utils:

Sebastian Riedel sri@cpan.org

Yuval Kogman nothingmuch@woobling.org

Robert Krimen <robertkrimen@gmail.com>

This software is copyright (c) 2010 by Robert Krimen.

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