求助一个关于Perl 继承 bless的问题

aaron_lidesheng

各位前辈好，本人初学Perl，在学习Perl OOO时 被bless问题深深困扰，先贴出我的学习代码和问题，希望各位大侠给指条明路:

父类 Bean.pm:

package Bean;
require Exporter;
@ISA = qw(Exporter);
@EXPORT = qw(setBeanType);

sub new {
        my $type = shift;
        my $this = {};
        $this->{"Bean"} = "Colombian";
        bless $this, $type;
        return this;
}

sub setBeanType {
        my ($class, $name) = @_;
        $class->{'Bean'} = $name;
        print "Set bean to $name \n";
}
1;

继承子类 Coffee.pm:
package Coffee;
require Exporter;
require Bean;
@ISA = qw(Exporter, Bean);
@EXPORT = qw(setImports, declareMain, closeMain);

sub new {
        my $type = shift;
        $this = Bean->new();
        $this->{'Coffee'} = 'Instant';
        bless $this, $type;
        return $this;
}

sub setCoffeeType {
        my ($class, $name) = @_;
        $class->{'Coffee'} = $name;
        print "Set coffee type to $name \n";
}
1;

调用Perl test.pl
push (@INC, 'cd');
use Coffee;

$cat = new Coffee;
print "\n-----------------------------Initial values-------------------\n";
print "Coffee: $cat->{'Coffee'} \n";
print "Bean: $cat->{'Bean'} \n";
print "\n-----------------------------Change Bean Type-----------------\n";
$cat->setBeanType('Mixed');
print "Bean Type is now $cat->{'Bean'} \n";
print "\n-----------------------------Change Coffee Type----------------\n";
$cat->setCoffeeType('Instant');
print "Type of coffee: $cup->{'Coffee'} \n";.

问题：
一运行test.pl，就报错Can't bless non-reference value at C:/Software/Programming/WorkSpace/Perl Practice/Coffee.pm line 17.
也就是Coffee构造函数中
bless $this, $type;
究竟是什么原因呢，求解。 本人环境是windows xp

kk861123

回复 1# aaron_lidesheng

1. sub new {
   
2.         my $type = shift;
   
3.         my $this = {};
   
4.         $this->{"Bean"} = "Colombian";
   
5.         bless $this, $type;
   
6.         return this;        # $this !!!
   
7. }
   
8. 
   

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