perl - 在 ex1.pl 第 4 行调用的未定义子例程 &main::add

Question

我有一个 perl 模块

MyMathLib.pm

package MyMathLib;
require Exporter;

@ISA = qw/EXPORTER/;

@EXPORT = qw/add/;

sub add
{
  $_[0] + $_[1];
}

1;

Ex1.pl

#!usr/bin/perl
#
use MyMathLib;
print add(1,2);

我收到以下错误:

Undefined subroutine &main::add called at ex1.pl line 4.

可能是什么原因？

Answer 1

它是导出商而不是导出商。

如果你包括

use strict;
use warnings;

在您的脚本中，您将激活 more checks这会向您展示问题的线索:

Can't locate package EXPORTER for @MyMathLib::ISA at Ex1.pl line 5.
Undefined subroutine &main::add called at Ex1.pl line 6.