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

my @a = mysub();
my %hash = (
            foo => scalar( my @b = mysub() ),
            bar => scalar @a,
            baz => scalar( mysub() ),
            boo => scalar(@{[ mysub() ]}),
            );

sub mysub {
    print "wantarray(): " . wantarray() . "\n";
    return ( 'bar', 'baz', 'blah' );
}

use Data::Dumper;
print Dumper(\%hash);