updated question: Initializing hashes of hashes

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

Dear Monks, I am trying to initialize a hash which gets its keys from an array. What am I doing wrong with the following piece of code?

use strict;
use warnings;
use Data::Dumper;
my $name = "Father" ;
my @terms = qw(Mom Wife Son Daughter);
my %fam_old = map{ $name => { $_,1 }} @terms;
print Dumper \%fam_old,"\n";
[download]

Only the key Daughter gets initialized to 1. Please correct my error. I am looking for a hash like this


$VAR1 = {
          "Father" => {
                       'Son' => 1,
                       'Daughter' => 1,
                         'Wife' => 1,
                       'Mom' => 1
                       };
         }
[download]

Comment on updated question: Initializing hashes of hashes Select or Download Code

Replies are listed 'Best First'.
Re: Initializing hashes of hashes by GrandFather (Saint) on Dec 19, 2015 at 21:48 UTC
If I add strictures (use strict; use warnings;) to your sample code: `use strict; use warnings; my $name = "Father" ; my @terms = qw(Mom Wife Son Daughter); my %fam_old = map{ $tool => { $_,1 }} @terms; print Dumper \%fam_old,"\n";` [download] it prints: `Global symbol "$tool" requires explicit package name at ...\noname.pl +line 6. Execution of ...\noname.pl aborted due to compilation errors.` [download] Mybe you intended the hash assignment to be: `my %fam_old = map{$_, 1} @terms;` [download] in which case the code prints: `$VAR1 = { 'Son' => 1, 'Daughter' => 1, 'Wife' => 1, 'Mom' => 1 }; $VAR2 = ' ';` [download] Premature optimization is the root of all job security	[reply] [d/l] [select]
Re: Initializing hashes of hashes by Discipulus (Canon) on Dec 19, 2015 at 21:52 UTC
the code is not complete, anyway you are telling to perl: fam_old is a list composed by the key tool that has Mom then Wife then Son then Daughter = 1. hoH are covered here Probably you want something like: `$fam_old{'tool'} = {map{$_=>1}@terms}; $VAR1 = { 'tool' => { 'Son' => 1, 'Wife' => 1, 'Mom' => 1, 'Daughter' => 1 } };` [download] L* after the UPDATE just change tool with father! 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]
Re: updated question: Initializing hashes of hashes by BillKSmith (Monsignor) on Dec 20, 2015 at 04:20 UTC
`use strict; use warnings; use Data::Dumper; my $name = "Father" ; my @terms = qw(Mom Wife Son Daughter); my %fam_old =( $name => { map{ $_=>1, } @terms} ); print Dumper \%fam_old;` [download] Output: `$VAR1 = { 'Father' => { 'Son' => 1, 'Wife' => 1, 'Mom' => 1, 'Daughter' => 1 } };` [download] Bill	[reply] [d/l] [select]
Re: Initializing hashes of hashes by Anonymous Monk on Dec 19, 2015 at 22:43 UTC
`my $name = "Father" ; my @terms = qw(Mom Wife Son Daughter); my %fam_old = map{ $name => { $_,1 }} @terms;` [download] is equivalent to `my $name = "Father" ; my %fam_old = ( $name => { 'Mom', 1 }, $name => { 'Wife', 1 }, $name => { 'Son', 1 }, $name => { 'Daugher', 1 }, );` [download] You only get 'Daugher' (associated with 'Father'), because your hash can have only one key 'Father'; so you get the last entry and not the rest of them.	[reply] [d/l] [select]