下面perl代码中的bless {_temperature => shift} => $class;语句如何理解!

Question

#!perl -w
use SOAP::Transport::HTTP;
SOAP::Transport::HTTP::CGI
    -> dispatch_to('Temperatures')
    -> handle;
package Temperatures;
sub f2c {
      my ($class, $f) = @_;
      return 5/9*($f-32);
  }
sub c2f {
      my ($class, $c) = @_;
      return 32+$c*9/5;
  }
sub new {
      my $self = shift;
      my $class = ref($self) || $self;
      bless {_temperature => shift} => $class;
  }
sub as_fahrenheit {
      return shift->{_temperature};
  }
sub as_celsius {
      return 5/9*(shift->{_temperature}-32);
  }

Answer 1

bless {_temperature => shift} => $class;
和
bless {_temperature => shift}， $class;
是一个意思

Answer 2

恩，那这里为什么可以把哈西{_temperature => shift},bless给自身的引用$class,平时不是都是bless ($self, $class) 这样使用的吗，这两者有什么区别???