adding keys to a hash

Anonymous Monk has asked for the wisdom of the Perl Monks concerning the following question:

given a list ( hashREF, ..., hashVAL ) where the ... contains a variable number of hashKEYS.

so i want the result to look like :

  $hashREF->{$key0}->{$key1}->{$key2} = $hashVAL
[download]

this snippet of code doesn't work. why?

my $list = [ "k0", "k1", "k2", ];
my ($h,$t);
foreach my $k ( @$list ) {
    $h->{$k} = {};
    $h = $h->{$k};
}
$h = $val;
[download]

thanks

Comment on adding keys to a hash Select or Download Code

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Re: adding keys to a hash by kyle (Abbot) on Mar 29, 2008 at 02:14 UTC
It doesn't work because your loop walks down a chain of hash references, but you don't retain the first reference in the chain anywhere, and at the end of the loop, you clobber the reference you have (`$h`) with some (presumably plain) scalar value (`$val`). I made some changes. `use Data::Dumper; my $list = [ "k0", "k1", "k2", ]; my ($h,$t); $t = $h = {}; foreach my $k ( @{$list}[ 0 .. $#{$list}-1 ] ) { $t->{$k} = {}; $t = $t->{$k}; } $t->{$list->[-1]} = 'val'; print Dumper $h; __END__ $VAR1 = { 'k0' => { 'k1' => { 'k2' => 'val' } } };` [download] Having gone through all that, however, you might want to look into Data::Diver for this kind of thing.	[reply] [d/l] [select]
Re: adding keys to a hash by Fletch (Bishop) on Mar 29, 2008 at 02:15 UTC
For that code in and of itself you don't keep a reference to the top / first hash so you've no way to get back the entire constructed value. Having said that, perhaps Data::Diver might do what you want off the shelf? The cake is a lie. The cake is a lie. The cake is a lie.	[reply]