This is a query about best practice in approaching this problem. The code below illustrates the problem, and the solution I have used (pre-defining a hashref). 
use strict;
my $href;
fill_hashref ($href);
print qq|TEST 1: $_\t$href->{$_}| for keys %$href; # Prints NOTHING

my $empty_hash_href={};
fill_hashref ($empty_hash_href);
print qq|TEST 2: $_\t$empty_hash_href->{$_}\n| for keys %$empty_hash_h
+ref; # Works as expected

sub fill_hashref{
   my ($lref) = @_;
   $lref->{RETURNVALUE}="I would like to see this";
}

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I'm guessing there is some coding design pattern with a best practice that wiser monks recognize here, and enlighten me : WWLD ? ( What would Larry do ?)

Update: Just to clarify - what I'm struggling with is that I occasionally forget to initialize the href passed in, and get bad results.

I am aware that an alternate solution is to use something like this in the sub: 

   $_[0]->{WHATEVER}="blah";

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But that has a certain ugliness (smell ?) to it, and was looking for a prettier, more aromatic solution.

While I am at it - how would this look/behave in perl6 ?

     Syntactic sugar causes cancer of the semicolon.        --Alan Perlis

In reply to Populating an undefined hashref in a sub by NetWallah

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