Here is a somewhat clunky delayed evaluation trick: 
my %f;
%f=(One=>1,
    two=>sub{$f{One}}
);

# Flatten all the subs ..
ref $f{$_} eq 'CODE' and $f{$_}=$f{$_}->() for keys %f;

print Dumper \%f; # All populated

[download]
Output: 
$VAR1 = {
          'two' => 1,
          'One' => 1
        };

[download]
Update: Verified that this works fine (i.e. 'One' and 'two' point to the same data) for HOH - i.e for: 
my %f;
%f=(One=>{this=>'that'},
    two=>sub{$f{One}});

[download]

        This is not an optical illusion, it just looks like one.

In reply to Re: Creating pointers in a HoH declaration by NetWallah
in thread Creating pointers in a HoH declaration by cmv

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