For a casual counter this might be overkill, but you could use a closure: 

use strict;
use warnings;
use Data::Dumper;

sub make_counter {
    my ( $tally, @labels ) = @_;
    return sub { $tally->{$_} += shift for @labels }
}

my %totals;
my $counter = make_counter \%totals, qw(a b c);

for(1..10){
    $counter->(1,2,3);
}
print Dumper \%totals;

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In reply to Re: += a hash slice? by hdb
in thread += a hash slice? by Random_Walk

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