继承

背景:

    讲到面向对象,不能只写出个类然后调用,根本优势在于继承来重用代码.Perl的继承虽然功能少些但简单实用.

 

正文:

父类, Person.pm

package Person; #包名, 最好与文件名相同


use Exporter; #父类必须


@ISA = qw(Exporter); #父类必须


@EXPORT = qw(setName); #父类必须,释放出该成员方法,以便继承



sub new{
  my $this = {}; #本质是一个哈希引用(指针),哈希是其成员列表,初始为空


  my $type = shift; #接收第一个参数,类名


  my %parm = @_; #接收全部参数到一个哈希


  $this->{'Name'} = $parm{'Name'}; #初始化各成员变量


  $this->{'Age'} = $parm{'Age'};
  bless $this, $type; #祝福给$type,此处是自己


  return $this; #返回对象


}

sub setName{
  my $this = shift; #接收第一个参数,对象本身,在包外调用


  $this->{'Name'} = shift; #开始接收其他参数


  print "call Person setName.\n";
}
1; #重点,包结尾

子类, Man.pm

package Man;
use Person; #使用父类

use Exporter; #子类非必须

@ISA = qw(Exporter, Person); #子类非必须

#@EXPORT = qw(setName);

sub new{
  my $type = shift;
  my $this = new Person('Name'=>"MJ", 'Age'=>50); #这就是继承,哈希里有了父类的成员

  bless $this, $type;
  return $this;
}

sub setName{ #重载,父子类均有该函数了

  my $this = shift;
  $this->{'Name'} = shift;
  print "call Man setName.\n"
}
1;

调用, callClass.pl

use Person;
use Man;
use strict;

#Person obj $jack

my $jack = new Person('Name'=>"jack wang", 'Age'=>23);
print "First Person Name:".$jack->{'Name'}."\n";
#Man obj $mj

my $mj = new Man;
print "First Man Name:".$mj->{'Name'}."\n";

$jack->setName("Blue zheng"); #父类setName

print "Second Person Name:".$jack->{'Name'}."\n";
print "Second Man Name:".$mj->{'Name'}."\n";
$mj->setName("KB"); #子类setName,如果子类没有重载,则调用父类setName

print "Third Person Name:".$jack->{'Name'}."\n";
print "Third Man Name:".$mj->{'Name'}."\n";
$mj->Person::setName("WD"); #强行调用父类setName

print "Forth Person Name:".$jack->{'Name'}."\n";
print "Forth Man Name:".$mj->{'Name'}."\n";

 

我想,这段代码对于刚写第一个面向对象的perl程序的人会有帮助的.