in reply to Re^2: Put references to array of hash elements in an array
in thread Put references to array of hash elements in an array

References work the other way round. \$AoH[0]{age} is a reference to the value stored under age, i.e. something like \42, it's no longer connected to the structure it came from.

You need to store the references in the @AoH if you want it to reflect the changes: 

#!/usr/bin/perl
use warnings;
use strict;

my @AoH;
my @age_ref = (42, 33);

@AoH = (
    { age => \$age_ref[0] },
    {},
    { age => \$age_ref[1] },
);


use Data::Dumper; print Dumper \@age_ref;

@age_ref = (1, 2);

use Data::Dumper; print Dumper \@AoH;

[download]

($q=q:Sq=~/;[c](.)(.)/;chr(-||-|5+lengthSq)`"S|oS2"`map{chr |+ord
}map{substrSq`S_+|`|}3E|-|`7**2-3:)=~y+S|`+$1,++print+eval$q,q,a,

[download]

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Re^4: Put references to array of hash elements in an array
by tel2 (Pilgrim) on Aug 03, 2018 at 07:41 UTC
    Thanks for that, choroba,

    If references work the other way round (i.e. I need to store the reference in the @AoH), then why does this code update the @AoH?:

    @AoH =
(
        { name => Adam, age => 0 },
        { name => Bob,  age => 10 },
        { name => Cat,  age => 20 }
);

@age_ref = (\$AoH[0]{age},\$AoH[2]{age});
${$age_ref[1]} = 23;
print "\$AoH[2]{age} = $AoH[2]{age}\n";
# The above prints '$AoH[2]{age} = 23'

    [download]

    Thanks.
    Tel2

[reply]
[d/l]
      When you assign to @AoH directly 
      @AoH = ...

      [download]

      the previous contents of the @AoH is irrelevant, the array now contains different elements. When you assign to something an elements references to, it changes the thing being referenced.

      ($q=q:Sq=~/;[c](.)(.)/;chr(-||-|5+lengthSq)`"S|oS2"`map{chr |+ord
}map{substrSq`S_+|`|}3E|-|`7**2-3:)=~y+S|`+$1,++print+eval$q,q,a,

      [download]
[reply]
[d/l]
[select]
        Thanks choroba,

        > "When you assing to @AoH directly (@AoH = ...) the previous contents of the @AoH is irrelevant, the array now contains different elements."

        Where in my code did I assign anything to @AoH directly via "@AoH = ..." apart from at the very beginning?

[reply]

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