blocks|key|321202|text|模块中有一个错误。Math::Counting+ISA+Exporter，但Math::Counting不加载Exporter。|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|321203|解决方法:您可以手动require或use+Exporter。|321204|更好的做法是:向模块作者提交bug，并提供测试用例。|321205|评论：|321206|哦，非常有趣。模块作者确实测试了他的函数，但是Test::More拉入了Exporter__，这意味着模块源代码中的这个省略没有被注意到。|321207|更新：|321208|Math::Counting+0.0904已发布，解决了此问题。|321209|entityMap|0|LINK|mutability|MUTABLE|url|http://search.cpan.org/perldoc/Math%253a%253aCounting|1|http://search.cpan.org/perldoc/Exporter|2|http://perldoc.perl.org/functions/require.html|3|http://perldoc.perl.org/functions/use.html|4|http://search.cpan.org/perldoc/Math%253a%253aCounting^0|O|3|12|E|1J|8|9|E|0|S|8|1|0|M|8|A|7|2|I|3|3|0|0|0|N|A|10|8|0|0|0|E|4|0^^$0|@$1|2|3|4|5|6|7|17|8|@$9|18|A|19|B|C]|$9|1A|A|1B|B|C]|$9|1C|A|1D|B|C]]|D|@$9|1E|A|1F|1|1G]|$9|1H|A|1I|1|1J]]|E|$]]|$1|F|3|G|5|6|7|1K|8|@$9|1L|A|1M|B|C]]|D|@$9|1N|A|1O|1|1P]|$9|1Q|A|1R|1|1S]]|E|$]]|$1|H|3|I|5|6|7|1T|8|@]|D|@]|E|$]]|$1|J|3|K|5|6|7|1U|8|@]|D|@]|E|$]]|$1|L|3|M|5|6|7|1V|8|@$9|1W|A|1X|B|C]|$9|1Y|A|1Z|B|C]]|D|@]|E|$]]|$1|N|3|O|5|6|7|20|8|@]|D|@]|E|$]]|$1|P|3|Q|5|6|7|21|8|@]|D|@$9|22|A|23|1|24]]|E|$]]|$1|R|3|-4|5|6|7|25|8|@]|D|@]|E|$]]]|S|$T|$5|U|V|W|E|$X|Y]]|Z|$5|U|V|W|E|$X|10]]|11|$5|U|V|W|E|$X|12]]|13|$5|U|V|W|E|$X|14]]|15|$5|U|V|W|E|$X|16]]]]

There is a bug in the module. <a href="http://search.cpan.org/perldoc/Math%3a%3aCounting" rel="nofollow">Math::Counting</a> <code>ISA</code> <a href="http://search.cpan.org/perldoc/Exporter" rel="nofollow">Exporter</a>, but <code>Math::Counting</code> does not load <code>Exporter</code>.

Workaround: You can <a href="http://perldoc.perl.org/functions/require.html" rel="nofollow">require</a> or <a href="http://perldoc.perl.org/functions/use.html" rel="nofollow">use</a> <code>Exporter</code> manually.

Better: File a bug with the module author, provide a test case.

<h3>Comment:</h3>

Oh, very interesting. The module author does test his functions, but <code>Test::More</code> pulls in <code>Exporter</code>, meaning that this omission from the module source was not noticed.

<h3>Update:</h3>

<a href="http://search.cpan.org/perldoc/Math%3a%3aCounting" rel="nofollow">Math::Counting</a> 0.0904 has been released, addressing this issue.

blocks|key|321174|text|Math::Counting似乎缺少require+Exporter;，因此它的任何函数都不会被导出到您的命名空间。|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|321175|entityMap|0|LINK|mutability|MUTABLE|url|http://search.cpan.org/perldoc/Math%253a%253aCounting^0|I|H|0|E|0|0^^$0|@$1|2|3|4|5|6|7|N|8|@$9|O|A|P|B|C]]|D|@$9|Q|A|R|1|S]]|E|$]]|$1|F|3|-4|5|6|7|T|8|@]|D|@]|E|$]]]|G|$H|$5|I|J|K|E|$L|M]]]]

It seems that <a href="http://search.cpan.org/perldoc/Math%3a%3aCounting" rel="nofollow">Math::Counting</a> is missing <code>require Exporter;</code> so none of it's functions are being exported to your namespace.

blocks|key|1213381|text|一位好心人向CPAN提交了一份关于我忘记的require语句的错误报告，在他提醒我之后，我修复了模块导出，包括关于“污染名称空间”的注释。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1213382|此外，我在文档中添加了一个说明，即它是用于现实世界应用程序的Math::BigInt->bfac()的“薄包装器”。当我做的时候，我找不到简单的排列或组合的计算方法。现在有太多的..。|offset|length|style|CODE|1213383|entityMap^0|0|U|K|0^^$0|@$1|2|3|4|5|6|7|J|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|K|8|@$D|L|E|M|F|G]]|9|@]|A|$]]|$1|H|3|-4|5|6|7|N|8|@]|9|@]|A|$]]]|I|$]]

After being alerted by a nice person who filed a bug report with CPAN regarding my forgotten require statement, I fixed up the module export, including the comment about "polluting the namespace."

Also, I added a note that it is a "thin wrapper" for <code>Math::BigInt-&gt;bfac()</code> for real world applications, in the docs. When I made it, I could not find simple computations for permutation or combination. Now there are a plethora...

blocks|key|1213826|text|当您使用use+Math::Counting调用Math::Counting模块时，它似乎没有导出阶乘方法。|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|1213827|CPAN页面执行以下操作|1213828|use+Math::Counting+':student';|code-block|syntax|javascript|1213829|然后，factorial方法被导出到您的名称空间中，您可以在不添加整个包名的情况下使用它。|1213830|entityMap^0|4|I|0|0|0|0^^$0|@$1|2|3|4|5|6|7|Q|8|@$9|R|A|S|B|C]]|D|@]|E|$]]|$1|F|3|G|5|6|7|T|8|@]|D|@]|E|$]]|$1|H|3|I|5|J|7|U|8|@]|D|@]|E|$K|L]]|$1|M|3|N|5|6|7|V|8|@]|D|@]|E|$]]|$1|O|3|-4|5|6|7|W|8|@]|D|@]|E|$]]]|P|$]]

It seems the Math::Counting module did not export the factorial method when you called it using <code>use Math::Counting</code>.

The CPAN page does the following 

<pre><code>use Math::Counting ':student';
</code></pre>

and afterwards the factorial method is exported into your namespace, and you can use it without prepending the entire package name.

blocks|key|1213349|text|看看Math::Counting的源代码，看看它是什么版本。您可以通过以下操作找到源所在的位置：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1213350|prompt>+perldoc+-l+Math::Counting|code-block|syntax|javascript|1213351|您还可以通过查看模块的$VERSION变量来查找大约90%25的时间模块的版本：|offset|length|style|CODE|1213352|use+Math::Dumper;
print+"The+version+of+Math::Dumper+is+$Math::Dumper::VERSION\n";|1213353|我刚刚下载了0.0902版本，下面的程序运行得很好：|1213354|#!+/usr/bin/env+perl
#
use+strict;
use+warnings;
use+feature+qw(say);

use+Math::Counting;

say+$Math::Counting::VERSION;
say+factorial(6);|1213355|我注意到在这个版本中，他有：|1213356|our+@ISA+=+qw(Exporter);
our+@EXPORT+=+qw(
++++factorial+permutation+combination
++++bfact+++++bperm+++++++bcomb
);|1213357|因此，看起来作者在这个特定版本中自动导出了他们的所有子例程。作者还定义了两组导出标签:student和big。|1213358|它可能是在更早的版本中，他没有定义@EXPORT，但使用了@EXPORT_OK+(这是更好的)，你必须这样做：|1213359|use+Match::Counting+qw(:student);|1213360|或|1213361|use+Math::Counting+qw(factorial);|1213362|entityMap^0|0|0|B|8|0|0|0|0|0|0|16|8|1F|3|0|H|7|T|A|0|0|0|0^^$0|@$1|2|3|4|5|6|7|18|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|19|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|1A|8|@$I|1B|J|1C|K|L]]|9|@]|A|$]]|$1|M|3|N|5|D|7|1D|8|@]|9|@]|A|$E|F]]|$1|O|3|P|5|6|7|1E|8|@]|9|@]|A|$]]|$1|Q|3|R|5|D|7|1F|8|@]|9|@]|A|$E|F]]|$1|S|3|T|5|6|7|1G|8|@]|9|@]|A|$]]|$1|U|3|V|5|D|7|1H|8|@]|9|@]|A|$E|F]]|$1|W|3|X|5|6|7|1I|8|@$I|1J|J|1K|K|L]|$I|1L|J|1M|K|L]]|9|@]|A|$]]|$1|Y|3|Z|5|6|7|1N|8|@$I|1O|J|1P|K|L]|$I|1Q|J|1R|K|L]]|9|@]|A|$]]|$1|10|3|11|5|D|7|1S|8|@]|9|@]|A|$E|F]]|$1|12|3|13|5|6|7|1T|8|@]|9|@]|A|$]]|$1|14|3|15|5|D|7|1U|8|@]|9|@]|A|$E|F]]|$1|16|3|-4|5|6|7|1V|8|@]|9|@]|A|$]]]|17|$]]

Take a look at the source code for Math::Counting and see what version it is. You can find where the source is located by doing this:

<pre><code>prompt&gt; perldoc -l Math::Counting
</code></pre>

You can also find the version of a module about 90% of the time by looking at the module's <code>$VERSION</code> variable:

<pre><code>use Math::Dumper;
print "The version of Math::Dumper is $Math::Dumper::VERSION\n";
</code></pre>

I just downloaded version 0.0902, and the following program works just fine:

<pre><code>#! /usr/bin/env perl
#
use strict;
use warnings;
use feature qw(say);

use Math::Counting;

say $Math::Counting::VERSION;
say factorial(6);
</code></pre>

I notice in this version, he has:

<pre><code>our @ISA = qw(Exporter);
our @EXPORT = qw(
 factorial permutation combination
 bfact bperm bcomb
);
</code></pre>

So, it looks like the author is automatically exporting all of their subroutines in this particular version. The author also has two groups of export tags defined <code>:student</code>, and <code>big</code>. 

It could be in earlier versions, he didn't have <code>@EXPORT</code> defined, but used <code>@EXPORT_OK</code> (which is preferable), and you had to do this:

<pre><code>use Match::Counting qw(:student);
</code></pre>

or

<pre><code>use Math::Counting qw(factorial);
</code></pre>

I am trying to use a module called <a href="http://search.cpan.org/perldoc/Math%3a%3aCounting">Math::Counting</a>:

<pre><code>#!/usr/bin/perl 

use strict;
use warnings;
use Math::Counting;

my $f = factorial(3);
print "$f\n";
</code></pre>

When I run it however, I get the following error

<pre><code>$ perl UsingModules.pl
Undefined subroutine &amp;main::factorial called at UsingModules.pl line 8.
</code></pre>

It seems like the function <code>factorial</code> is not being exported, but why?

When I used the following

<pre><code>my $f = Math::Counting::factorial(3);
</code></pre>

instead of what was above, it works perfectly fine, but I am curious why the function cannot be exported.

I am using <code>perl</code> v5.10.1 on Cygwin.

Perl module error regarding "undefined subroutine"

翻译质量差，导致语言生硬或混乱。

没有提供实际的解决方法或示例。

解答不清晰，无法理解或解决问题。

页面排版不美观，阅读体验差。

文章

问答

视频

学习中心

腾讯云实验室

直播

竞赛

腾讯云代码分析专区

腾讯iOA零信任安全管理系统专区

腾讯云架构师技术同盟交流圈

腾讯云数据库专区

腾讯云顾问专区

腾讯云原生专区

腾讯混元专区

腾讯云TCE专区

腾讯云Lighthouse专区

腾讯云HAI专区

腾讯云Edgeone专区

腾讯云存储专区

腾讯云智能专区

腾讯轻联专区 

腾讯云开发专区

TAPD专区

腾讯轻量云游戏服专区

腾讯云最具价值专家

腾讯云架构师技术同盟

腾讯云创作之星

腾讯云开发者先锋

腾讯云代码助手

云原生构建

TAPD 敏捷项目管理

Cloud Studio

SDK中心

API中心

命令行工具

涵盖代码开发、场景应用、自动测试全流程，助你从零构建专属AI助手

一站式MCP教程库，解锁AI应用新玩法

我正在尝试使用一个名为的模块#!/usr/bin/perl use strict;use warnings;use Math::Counting;my $f = factorial(3);print "$f\n";但是，当我运行它时，我得到以下错误$ perl UsingModules.plUndefined subroutine &main::factorial called at UsingM

问关于“未定义的子例程”的Perl模块错误
EN

回答 5

Stack Overflow用户

Stack Overflow用户

Stack Overflow用户

社区

活动

圈层

关于

腾讯云开发者

热门产品

热门推荐

更多推荐

问关于“未定义的子例程”的Perl模块错误EN

回答 5

Stack Overflow用户

Stack Overflow用户

Stack Overflow用户

社区

活动

圈层

关于

腾讯云开发者

热门产品

热门推荐

更多推荐

问关于“未定义的子例程”的Perl模块错误
EN