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Some more details: in this post someone asked how to "take strings like:"

/file.txt /a/file.txt /a/b/c /a/b/c/file.txt /z/m/w/file.txt

and "produce something like:"

%dir_hash( 'file.txt' => '', 'a' => { 'file.txt' => '', 'b' => { 'c' => { 'file.txt'
[snip]

In my reply I pointed out that there should be a module designed for exactly this kind of things, which I still fail to remember. (Hey, anyone here? Update: It's Data::Diver, thanks to tye!) But first of all I provided a minimal example to accomplish not exactly the same task, but a very close one; the original code is as follows:

#!/usr/bin/perl use strict; use warnings; use Data::Dumper; my %dirhash; while (<DATA>) { chomp; my $last=\%dirhash; $last=$last->{$_} ||= {} for split qr|/|; } print Dumper \%dirhash; __END__ /file.txt /a/file.txt /a/b/c /a/b/c/file.txt /z/m/w/file.txt

In it I have to compensate for perl not autovivifying in this case. Then Brian McCauley provided an alternative way, precisely suggesting that one do

my $last=\\%dirhash; $last=\$$last->{$_} for split qr|/|;

Instead, which is the Autovivification trick I'm "advertising" here.


In reply to Re: Autovivification trick by blazar
in thread Autovivification trick by blazar

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