另外，分享一篇好文： http://www.stonehenge.com/merlyn/PerlJournal/col04.html
2010/4/12 cnhack TNT <[email protected]> > *print '[', $self->name, " is being destroyed...]\n"; > * > 猜你的本意是： > > * print '[', ref $self, " is being destroyed...]\n"; > > 改成如上这样就OK了，这是因为 $self 此时是 Barn, 没有 name 这个方法，直接就异常退出了。* > > > > 2010/4/8 andy white <[email protected]> > > { package Animal; >> sub name { >> my $either = shift; >> ref $either >> ? $either->{Name} >> : "an unnamed $either"; >> } >> sub named { >> my $class = shift; >> my $name = shift; >> my $self = { Name => $name, Color => $class->default_color }; >> bless $self, $class; >> } >> >> sub default_color { 'brown' } >> sub DESTROY { >> my $self = shift; >> print '[', $self->name, " has died.]\n"; >> } >> } >> { package Cow; >> @ISA = qw( Animal ); >> } >> { package Barn; >> sub new { bless [ ], shift } >> sub add { push @{+shift}, shift } >> sub contents { @{+shift} } >> sub DESTROY { >> my $self = shift; >> print '[', $self->name, " is being destroyed...]\n"; >> for($self->contents) { >> print ' ', $_->name, " goes homeless.\n"; >> } >> } >> } >> >> my $barn = Barn->new; >> $barn->add(Cow->named('Bessie')); >> $barn->add(Cow->named('Gwen')); >> print "Burn the barn:\n"; >> $barn = undef; >> print "End of program.\n"; >> >> 现在的程序的运行结果的是： >> Burn the barn: >> [Gwen has died.] >> [Bessie has died.] >> End of program. >> >> 当$barn = undef时，调用的是Animal的DESTROY方法。 >> >> 我想要的结果是还要调用Barn的DESTROY方法(并且打印contents的内容)，即 >> Burn the barn: >> Barn=ARRAY(0x541c) is being destroyed... >> Bessie goes homeless. >> Gwen goes homeless. >> [Gwen has died.] >> [Bessie has died.] >> End of program. >> >> 问题出在那里阿？那位帮忙看看吧！ >> >> -- >> 您收到此邮件是因为您订阅了 Google 网上论坛的“PerlChina Mongers 讨论组”论坛。 >> 要向此网上论坛发帖，请发送电子邮件至 [email protected]。 >> 要取消订阅此网上论坛，请发送电子邮件至 >> [email protected]<perlchina%[email protected]> >> 。 >> 若有更多问题，请通过 http://groups.google.com/group/perlchina?hl=zh-CN 访问此网上论坛。 >> > > -- 您收到此邮件是因为您订阅了 Google 网上论坛的“PerlChina Mongers 讨论组”论坛。 要向此网上论坛发帖，请发送电子邮件至 [email protected]。 要取消订阅此网上论坛，请发送电子邮件至 [email protected]。 若有更多问题，请通过 http://groups.google.com/group/perlchina?hl=zh-CN 访问此网上论坛。
