"1"是什么意思?在Perl中意味着什么? [英] What does "1;" mean in Perl?

问题描述

我遇到了一些Perl模块，例如，它们看起来类似于以下代码:

I have come across a few Perl modules that for example look similar to the following code:

package MyPackage;

use strict;
use warnings;
use constant PERL510  => ( $] >= 5.0100 );

require Exporter;

our @ISA = qw(Exporter);  
our @EXPORT = qw( );

{  #What is the significance of this curly brace?

    my $somevar;

    sub Somesub {
      #Some code here 
    }
}

1;

1;以及包围$somevar和Sub的花括号的意义是什么?

What is the significance of 1; and of the curly braces that enclose the $somevar and the Sub?

推荐答案

1表示该模块将true返回到use/require语句.它可以用来判断模块初始化是否成功.否则，use/require将失败.

1 at the end of a module means that the module returns true to use/require statements. It can be used to tell if module initialization is successful. Otherwise, use/require will fail.

$somevar是只能在块内部访问的变量.它用于模拟静态"变量.从Perl 5.10开始，可以使用关键字 state 关键字获得相同的结果:

$somevar is a variable which is accessable only inside the block. It is used to simulate "static" variables. Starting from Perl 5.10 you can use keyword state keyword to have the same results:

## Starting from Perl 5.10 you can specify "static" variables directly.
sub Somesub {
    state $somevar;
}

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