Perl - undefined subroutine

Question

I have the following Perl code:

use Email::Sender::Simple;
use IO::Socket::SSL;

IO::Socket::SSL::set_defaults(SSL_verify_mode => SSL_VERIFY_NONE);

Email::Sender::Simple::sendmail($email, { transport => $transport });

When I run it I get this error:

Undefined subroutine &Email::Sender::Simple::sendmail called at script.pl line 73.

If I change the code to have the following, then it works:

use Email::Sender::Simple qw(sendmail);

sendmail($email, { transport => $transport });

Can someone explain why I had to change the code for sendmail, while I did NOT have to change the code for set_defaults to look like:

use IO::Socket::SSL qw(set_defaults);

set_defaults(SSL_verify_mode => SSL_VERIFY_NONE);

Well I just tried changing my code to have use IO::Socket::SSL qw(set_defaults); and set_defaults(SSL_verify_mode => SSL_VERIFY_NONE); and I got an error saying "set_defaults" is not exported by the IO::Socket::SSL module — pacoverflow
– pacoverflow, Commented Aug 12, 2013 at 2:12

David W. · Accepted Answer · 2013-08-12 02:23:09Z

4

Take a look at the code Email/Sendmail/Simple.pm. There is no sendmail subroutine in that program. Instead, if you look at the header, you'll see:

use Sub::Exporter -setup => {
  exports => {
    sendmail        => Sub::Exporter::Util::curry_class('send'),
    try_to_sendmail => Sub::Exporter::Util::curry_class('try_to_send'),
  },
};

I'm not familiar with Sub::Exporter, but I did notice this description.

The biggest benefit of Sub::Exporter over existing exporters (including the ubiquitous Exporter.pm) is its ability to build new coderefs for export, rather than to simply export code identical to that found in the exporting package.

Oh...

So, the purpose of using Sub::Exporter is to export subroutine names that aren't subroutines in your package.

If you're interested, you can read the tutorial of Sub::Exporter, but it appears it has the ability to export subroutines under different names.

Thus, Email::Sender::Simple::sendmail isn't a subroutine, but that sendmail can still be exported.

answered Aug 12, 2013 at 2:23

David W.

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2 Comments

justintime Over a year ago

Maybe too much detail, but I can see where set_defaults is exported by IO::Socket::SSL

ikegami Over a year ago

If you wanted to avoid importing, you could use Email::Sender::Simple->send(...) instead of Email::Sender::Simple::sendmail(...).

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