Technique, the first: we just assign a new reference to $ref, so that the pointer is pointing to the baz array.

use Data::Dumper;

my $VAR1 = { "baz" => [1,2,3,4] };
my $VAR2 = $VAR1;

print "BEFORE\n", Dumper($VAR1, $VAR2);

# Note $VAR1 is changed, but $VAR2 is still the hashref.
replace_ref($VAR1);

print "AFTER\n", Dumper($VAR1, $VAR2);

sub replace_ref {
    $_[0] = $_[0]{baz};
}

[download]

Technique, the second: we actually swap the hash and array around in memory. This swaps all references to them!

use Data::Dumper;
use Data::Swap;

my $VAR1 = { "baz" => [1,2,3,4] };
my $VAR2 = $VAR1;

print "BEFORE\n", Dumper($VAR1, $VAR2);

# Note that both $VAR1 and $VAR2 are changed.
replace_ref($VAR1);

print "AFTER\n", Dumper($VAR1, $VAR2);

sub replace_ref {
    swap $_[0], $_[0]{baz};
}

[download]
perl -E'sub Monkey::do{say$_,for@_,do{($monkey=[caller(0)]->[3])=~s{::}{ }and$monkey}}"Monkey say"->Monkey::do'

In reply to Re: Replace Hash-Ref with Array-Ref by tobyink
in thread Replace Hash-Ref with Array-Ref by Anonymous Monk

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