Nicholas Clark wrote:
Well, I assume that the do-nothing sub is assigned into the variable, and
gets re-evaluated each time the variable is use. Which would mean that you'd
get a new (different) empty hash each time. Whereas an empty hash constructor
gives you a hash reference to keep. (not just for Christmas)

Hmm, I think the type of value stored in $foo after

   my $foo = {};

is Code ^ Hash which is viable for &postfix:{'<','>'} which when
assigned to drops the Code from the type. And I further think that
a plain {} empty code literal doesn't have the is rw property set
and thus something like

  $foo()<blahh> = 23;

is not allowed. The above shall mean that the code in $foo is evaluated,
delivers a fresh, empty hash which gets the kv blahh => 23 and then is

It's like the autovivification bug:

sub stuff {
  my $h = shift;

Do you consider that a Perl5 bug or a program bug? I find it
inconsistent with respect to $h beeing either a const alias
to $a and thus always a detached copy after the shift or it
should always install the autovivified hash also into $a. But
the mixed mode of directly accessing the hashref in $a if it
refers to a hash already is at best surprising. The Perl6
sub declarations make this much clearer:

  sub stuff (%h is rw)

my $a;
$a->{$_}++ for @ARGV;

print "$a->{k}\n";

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