perl use base 继承

centos6.5:/root/podinns/lib#cat First.pm
package First;
use base qw(Second);
sub new {
    my $self = {};
    my $invocant = shift;
my $class = ref($invocant) || $invocant;
    my ($name)=@_;
      my $self = {
         "name" =>"luotuo",
         @_ # 覆盖以前的属性
                 };
    bless $self, $class; # Use class name to bless() reference
    return $self;  

};  

sub sum {
       $self=shift;
       my $a=shift;
       my $b=shift;
       return $a + $b;
};
1;
centos6.5:/root/podinns/lib#cat Second.pm
package Second;
sub sum_all {
       $self=shift;
       my $a=shift;
       my $b=shift;
       return $a * $b;
};  

sub sum_x {

       my $a=shift;

       my $b=shift;

       return $a * $b;

};
1;
centos6.5:/root/podinns/lib#cat a2.pl
unshift(@INC,"/root/podinns/lib");
use First;
$ed=First->new('name'=>'poddinns');
print "111111111111111\n";
print $ed->sum(12,34);
print "\n";
print "2222222222222222\n";
print $ed->sum_all(12,34);
print "\n";
print "333333333333333333\n";
print Second::sum_x(12,21);
print "\n";
centos6.5:/root/podinns/lib#perl a2.pl
111111111111111
46
2222222222222222
408
333333333333333333
252