Perl中的"use base"和@ISA有什么区别? [英] What's the difference between `use base` and @ISA in Perl?

问题描述

我想制作一个扩展DBI的单例类.我应该做这样的事情吗?

I want to make a singleton class which extends DBI. should I be doing something like this:

use base 'Class::Singleton';
our @ISA = ('DBI');

或者这个:

our @ISA = ('Class::Singleton', 'DBI');

还是其他?

不太清楚'use base'和'isa'之间的区别是什么.

Not really sure what the difference between 'use base' and 'isa' is.

推荐答案

@ISA的典型用法是

package Foo;

require Bar;
our @ISA = qw/Bar/;

base和parent编译指示均加载请求的类并修改@ISA使其包含:

The base and parent pragmas both load the requested class and modify @ISA to include it:

package Foo;

use base qw/Bar/;

如果要多重继承，可以为base或parent提供多个模块:

If you want multiple inheritance, you can supply more than one module to base or parent:

package Foo;

use parent qw/Bar Baz/; #@ISA is now ("Bar", "Baz");

parent编译指示从Perl 5.10.1开始是新的，但是如果您具有较旧的Perl版本，则可以从CPAN安装该编译指示.之所以创建它，是因为base杂项由于堆积在其中的残骸"而变得难以维护.您应该不会在两者的基本用法上看到差异.

The parent pragma is new as of Perl 5.10.1, but it is installable from CPAN if you have an older version of Perl. It was created because the base pragma had become difficult to maintain due to "cruft that had accumulated in it." You should not see a difference in the basic use between the two.

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