PerlCritic 示例：循环迭代器不是词法的

Posted 2023-03-24

【中文标题】PerlCritic 示例：循环迭代器不是词法的

【英文标题】：PerlCritic example: loop iterator is not lexical

【发布时间】：2022-01-17 21:50:11

【问题描述】：

在调试一些较旧的 perl 代码时，我使用 perlcritic 作为一种发现错误的方法。 我经常偶然发现这个“循环迭代器不是词法”策略： Perl::Critic::Policy::Variables::RequireLexicalLoopIterators 而且它从来都不是错误。 当我在测试程序中实现作者的示例时，我似乎没有重现它试图解决的问题：

#!/usr/bin/perl
use strict;
use warnings;
use diagnostics;

my $bicycle = is_red => 1, has_baseball_card_in_spokes => 1, has_bent_kickstand => 1, locked => 1;

my $bicycle1 = is_green => 1, has_baseball_card_in_spokes => 1, has_bent_kickstand => 1, locked => 1;

my $bicycle2 = is_blue => 1, has_baseball_card_in_spokes => 0, has_bent_kickstand => 0, locked => 1;

my @things_attached_to_the_bike_rack = ($bicycle,$bicycle1,$bicycle2);

for $bicycle (@things_attached_to_the_bike_rack) 
    if (
            $bicycle->is_red
        and $bicycle->has_baseball_card_in_spokes
        and $bicycle->has_bent_kickstand
    ) 
        $bicycle->locked = 0;

        last;
    


if ( $bicycle and !$bicycle->locked ) 
    print "riding home in time for dinner\n";

诚然，我没有用函数创建一个有福的对象，而是一个哈希引用，所以它可能与 Perl 中的对象有关。 即使我重新安排阵列的顺序，我每次都会及时回家吃晚饭。 所以我肯定遗漏了一些明显的东西，我想要一个可重现的例子来说明这是一个问题的情况。

我知道有old questions about this，但我想知道这是否仍然是 2021 年末的相关政策。

【参考方案1】：

您的代码与策略示例不同。您的代码在循环外为 $bicycle 分配了一个值，而策略示例没有。

以下代码更能代表策略示例的意图：

use strict;
use warnings;
use diagnostics;

my $bicycle0 = is_red => 1, has_baseball_card_in_spokes => 1, has_bent_kickstand => 1, locked => 1;
my $bicycle1 = is_green => 1, has_baseball_card_in_spokes => 1, has_bent_kickstand => 1, locked => 1;
my $bicycle2 = is_blue => 1, has_baseball_card_in_spokes => 0, has_bent_kickstand => 0, locked => 1;

my @things_attached_to_the_bike_rack = ($bicycle0, $bicycle1, $bicycle2);

my $bicycle;
for $bicycle (@things_attached_to_the_bike_rack) 
    if (
            $bicycle->is_red
        and $bicycle->has_baseball_card_in_spokes
        and $bicycle->has_bent_kickstand
    ) 
        $bicycle->locked = 0;

        last;
    


if ( $bicycle and !$bicycle->locked ) 
    print "riding home in time for dinner\n";

当我运行它时，我没有看到 riding home in time for dinner 消息，正如我在运行您的原始代码时所看到的那样。