Dynamically create the hash reference

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

Hi All,

I am trying to create dynamic references in a recursion function. Below I place code which I try, and it return '{}' only. How to get the initial level reference in else part?

use Data::Dumper;

sub insert {
  my ($ref, $head, @tail) = @_;
   return unless ( @tail );
  if ( @tail and $head ne 'break') { insert( \%{$ref->{$head}}, @tail 
+) }
  else {
      # Here $ref gives '{}' value only.
      # How to get values of previous head values (ie. f1,f2,f3)
      print "\n==>", Dumper $ref;

      # More commands . . .
      #insert( \%{$ref->{f1}}, @tail )
  }
}


my %hash;
while (<DATA>) {
chomp and insert \%hash, split( '/', $_ ) ;
}
print "\nDump\n", Dumper %hash;

__DATA__
f1/f2/f3/f4/break/f1/f2/f5/break/f1/f2/f6
[download]

Comment on Dynamically create the hash reference Download Code

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Re: Dynamically create the hash reference by choroba (Cardinal) on Oct 07, 2015 at 11:09 UTC
In order to be able to return back to the top of the hash, you have to include the top reference to the arguments. #!/usr/bin/perl use warnings; use strict; use Data::Dumper; sub insert { my ($top, $ref, $head, @tail) = @_; return unless @tail; if ('break' eq $head) { insert($top, $top, @tail); } else { # Don't overwrite existing paths. $ref->{$head} = {} unless exists $ref->{$head}; insert($top, $ref->{$head}, @tail); } } my %hash; while (<DATA>) { chomp; # Add a dummy end not to throw the last entry away. insert(\%hash, \%hash, split(m=/=), '/.'); } print "\nDump\n", Dumper(\%hash); __DATA__ f1/f2/f3/f4/break/f1/f2/f5/break/f1/f2/f6 [download] See also Data::Diver. Update: Data::Diver example added. `while (<DATA>) { chomp; for my $path (split m=/break/=) { DiveVal(\%hash, split m=/=, $path); } }` [download] لսႽ† ᥲᥒ⚪⟊Ⴙᘓᖇ Ꮅᘓᖇ⎱ Ⴙᥲ𝇋ƙᘓᖇ	[reply] [d/l] [select]
Re^2: Dynamically create the hash reference by k_manimuthu (Monk) on Oct 07, 2015 at 12:29 UTC
@choroba You point me into right direction. Thanks a lot.	[reply]
Re: Dynamically create the hash reference by Discipulus (Canon) on Oct 07, 2015 at 10:31 UTC
hello k_manimuthu i'm not sure to well understand your question.. what is the desired hash that you want to pull from that data? L* There are no rules, there are no thumbs.. Reinvent the wheel, then learn The Wheel; may be one day you reinvent one of THE WHEELS.	[reply] [d/l]