`use` 包范围:如何使其跨文件?

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问题描述

在scriptA.pl中，有use DBI

在scriptB.pl中，有require "scriptA.pl"

但是我们仍然不能在scriptB.pl

除了在 scriptB.pl 中重复 use DBI 之外，还有什么方法可以解决这个问题?

Any way to handle this except repeating use DBI in scriptB.pl?

推荐答案

use 是一个文档化的特性:

The scoped nature of use is a documented feature:

从命名模块将一些语义导入当前包，通常是通过将某些子例程或变量名称别名到您的包中.

您可以通过回到石器时代来做您想做的事，如下例所示，但请不要这样做.

You could do what you want by going back to the stone age as in the following example, but please don't.

使用 MyModule 作为 DBI 的替代:

Using MyModule as a stand-in for DBI:

package MyModule;

use Exporter 'import';
our @EXPORT = qw/ foo /;
sub foo { print "$_[0]!\n" }

1;

然后从 scriptA.pl

foo "from scriptA";

和来自 scriptB.pl

foo "from scriptB";

全部从一个主程序开始

#! /usr/bin/perl

use warnings;
use strict;

use MyModule;

do "scriptA.pl" or die;
do "scriptB.pl" or die;

print "done.\n";

给出以下输出:

from scriptA!
from scriptB!
done.

您也可以在讨厌的 eval 游戏中禁用范围安全功能，但也请不要这样做.

You also could disable the scoping safety-feature with nasty eval games, but please don't do that either.

如果您的设计需要改进——也许 scriptA 和 scriptB 属于同一个包——那将是更好的时间投资.否则，硬着头皮花费九次击键.

If your design needs improvement—maybe scriptA and scriptB belong in the same package—that would be a far better investment of your time. Otherwise, bite the bullet and expend nine keystrokes.

请注意，在运行时通过 do 或 require 执行 Perl 库是一种严重过时的方法.perlmod 文档描述了现代方法.

Please note that executing Perl libraries at runtime via do or require are a seriously dated approaches. The perlmod documentation describes the modern approach.

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