in reply to Re^2: Recursively walk a hash to get to an element
in thread Recursively walk a hash to get to an element

The code I posted was based on code that did use :lvalue, but I adapted it to match the OP.

Original:

I strongly recommend using an existing solution such as Data::Diver.

use Data::Diver qw( DiveVal ); my @keys = map "level$_", 1 .. 3; my $branch = {}; DiveVal($branch, map \$_, @keys) = 'leaf'; -or- my %branch; DiveVal(\%branch, map \$_, @keys) = 'leaf';

Obviously, it can be done without module too.

sub DiveVal :lvalue { my $p = \shift; $p = \( $$p->{$_} ) for @_; $$p } my @keys = map "level$_", 1 .. 3; my $branch; DiveVal($branch, @keys) = 'leaf'; -or- my %branch; DiveVal(\%branch, @keys) = 'leaf';

How my DiveVal works:

Pre-loop: $p references $branch After loop pass 0: $p references $branch->{level1} After loop pass 1: $p references $branch->{level1}{level2} After loop pass 2: $p references $branch->{level1}{level2}{level3} Returned: $branch->{level1}{level2}{level3}

The extra level of indirection has many benefits.

Being fundamentally the same solution, the explanation applies to Merlyn's code too. Just substitute $a for $p, and it's a reference to the final scalar that's returned instead of the scalar itself as an lvalue.