Adding some syntactic sugar with prototype and lvalue (not sure when the + prototype was introduced UPDATE: 5.14.0 code corrected)

Checking the ref-type would help diving arrays too. (but would probably reinvent Data::Diver )

use v5.14;
use warnings;
use Test::More;


sub dive(+;@) :lvalue {
    my $h = \ shift;

    $h = \($$h->{$_}) for @_;

    $$h;
}


my %hsh;
my $h_ref = \%hsh;

my $val = $hsh{a}{b}{c} = 3;
my $val2 = 42;

my @path = qw/a b c/;

my $test;


;;;;;;;;;; $test = "Prototypes";

is( dive(%hsh  => @path) , $val, "$test accepts \%list form");
is( dive($h_ref=> @path) , $val, "$test accepts \$ref  form");


;;;;;;;;;; $test = "assign directly to lvalue";

dive(%hsh=> @path) = $val2;

is( $hsh{a}{b}{c}, $val2, $test);


;;;;;;;;;; $test = "increment in place";

dive( %hsh=> @path )++;

is( $hsh{a}{b}{c}, ++$val2, $test);


;;;;;;;;;; $test = "grab scalar reference";

my $s_ref = \ dive(%hsh, @path);

$$s_ref++;

is( $hsh{a}{b}{c}, ++$val2, $test);


;;;;;;;;;; $test = "aliasing";

for my $alias ( dive(%hsh, @path) ) {
    $alias++;
}

is( $hsh{a}{b}{c}, ++$val2, $test);



done_testing;

[download]
OUTPUT: 
ok 1 - Prototypes accepts %list form
ok 2 - Prototypes accepts $ref  form
ok 3 - assign directly to lvalue
ok 4 - increment in place
ok 5 - grab scalar reference
ok 6 - aliasing
1..6

[download]

UPDATE: cosmetic corrections

Cheers Rolf
(addicted to the Perl Programming Language :)
Wikisyntax for the Monastery

In reply to Re^2: Recursively walk a hash to get to an element by LanX
in thread Recursively walk a hash to get to an element by merlyn

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