sub _set {
    my $self = shift;
    my ($key, $value);
    while (($key, $value) = splice @_, 0, 2) { $self->{$key} = $value }
}

##</code><code>##

c:\@Work\Perl\monks>perl -wMstrict -MData::Dump -le
"sub _set {
   my $self = shift;
   %$self = (%$self, @_);
   }
 ;;
 my $hr = bless { qw(y 25  z 26) };
 ;;
 $hr->_set(qw(a 1  b 2  c 3));
 dd $hr;
"
bless({ a => 1, b => 2, c => 3, "y" => 25, z => 26 }, "main")