sub new {
    my( $class, $hashRef )= @_;
    my $self= bless {%$hashRef}, $class;
    return $self;
}
# or
sub new {
    my( $class, $hashRef )= @_;
    my $self= bless {}, $class;
    @{$self}{keys %$hashRef}= values %$hashRef;
    return $self;
}
# or
sub new {
    my( $class, $hashRef )= @_;
    my $self= bless {}, $class;
    %$self= %$hashRef;
    return $self;
}
# etc.