我理解bless了，哈哈，给大家个例子。

CODE:

#!/usr/bin/perl -w
package person;
use strict;

sub sleep() {
        my ($self) = @_;
        my $name = $self->{"name"};

        print("$name is person, he is sleeping\n");
}

sub study() {
        my ($self) = @_;
        my $name = $self->{"name"};

        print("$name is person, he is studying\n");
}
return 1;

CODE:

#!/usr/bin/perl -w
package dog;
use strict;

sub sleep() {
        my ($self) = @_;
        my $name = $self->{"name"};

        print("$name is dog, he is sleeping\n");
}

sub bark() {
        my ($self) = @_;
        my $name = $self->{"name"};

        print("$name is dog, he is barking\n");
}

return 1;

CODE:

#!/usr/bin/perl =w
use strict;
use person;
use dog;

sub main()
{
        my $object = {"name" => "tom"};

        # 先把"tom"变为人
        bless($object, "person");
        $object->sleep();
        $object->study();

        # 再把"tom"变为狗
        bless($object, "dog");
        $object->sleep();
        $object->bark();

        # 最后，再把"tom"变回人
        bless($object, "person");
        $object->sleep();
        $object->study();
}

&main();

# 程序运行时输出：
# tom is person, he is sleeping
# tom is person, he is studying
# tom is dog, he is sleeping
# tom is dog, he is barking
# tom is person, he is sleeping
# tom is person, he is studying

CODE:

#!/usr/bin/perl =w
use strict;
use person;
use dog;

sub main()
{
        my $object = {"name" => "tom"};

        # 没有把类型信息和$object绑定，因此无法获知$object有sleep方法
        $object->sleep();
        $object->study();
}

&main();

# 程序运行输出为：
# Can't call method "sleep" on unblessed reference at bless.wrong.pl line 10.

CODE:

#include <stdio.h>
#include <stdlib.h>
#include <string.h>

struct object {
        char name[16];
};

struct person {
        char name[16];

        void sleep() { printf("%s is person, he is sleeping\n", this->name); }
        void study() { printf("%s is person, he is studying\n", this->name); }
};

struct dog {
        char name[16];

        void sleep() { printf("%s is dog, he is sleeping\n", this->name); }
        void bark() { printf("%s is dog, he is barking\n", this->name); }
};

#define bless(object, type) ((type*) object)

int main()
{
        struct object * o = (struct object *) malloc(sizeof(struct object));
        strcpy(o->name, "tom");

        // 先把"tom"变为人
        bless(o, person)->sleep();
        bless(o, person)->study();

        // 再把"tom"变为狗
        bless(o, dog)->sleep();
        bless(o, dog)->bark();

        // 最后，再把"tom"变回人
        bless(o, person)->sleep();
        bless(o, person)->study();
        return 0;
}

// 程序运行时输出：
// tom is person, he is sleeping
// tom is person, he is studying
// tom is dog, he is sleeping
// tom is dog, he is barking
// tom is person, he is sleeping
// tom is person, he is studying

QUOTE:

原帖由 royalzhang 于 2007-8-24 14:34 发表
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QUOTE:

原帖由 pengchy 于 2007-8-25 12:46 发表
还以为bless只能用在.pm文件中呢！

QUOTE:

原帖由 DennisRitchie 于 2007-8-27 02:02 发表

perl的bless关键字对初学者是一个难点，部分原因就是bless的"英文含义"与它perl中的含义毫无关联，可以说是“驴头不对马嘴”！

QUOTE:

原帖由 福瑞哈哥 于 2007-8-27 11:15 发表


拜托放轻松一些，编程也不要总是正襟危坐好不好？
怎么能说bless与它在perl中的含义毫无关联呢？
一个死气沉沉的引用，经过赐福，就神气活现地具有了某种灵性，这个词难道用的还不好吗？