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Cover image for Frenemies part 2: What a difference a (Perl) module makes
Mark Gardner
Mark Gardner

Posted on • Originally published at phoenixtrap.com on

5

Frenemies part 2: What a difference a (Perl) module makes

Last week I explored using the Inline::Perl5 module to port a short Perl script to Raku while still keeping its Perl dependencies. Over at the Dev.to community, Dave Cross pointed out that I could get a bit more bang for my buck by letting his Feed::Find do the heavy lifting instead of WWW::Mechanize’s more general-purpose parsing.

A little more MetaCPAN investigation yielded XML::Feed, also maintained by Dave, and it had the added benefit of obviating my need of XML::RSS by not only discovering feeds but also retrieving and parsing them. It also handles the Atom syndication format as well as RSS (hi daxim!). Putting it all together produces the following much shorter and clearer Perl:

#!/usr/bin/env perl
use v5.12; # for strict and say
use warnings;
use XML::Feed;
use URI;
my $url = shift @ARGV || 'https://phoenixtrap.com';
my @feeds = XML::Feed->find_feeds($url);
my $feed = XML::Feed->parse( URI->new( $feeds[0] ) )
or die "Couldn't find a feed at $url\n";
binmode STDOUT, ':encoding(UTF-8)';
say $_->title, "\t", $_->link for $feed->entries;
view raw feed_finder2.pl hosted with ❤ by GitHub

And here’s the Raku version:

#!/usr/bin/env raku
use XML::Feed:from<Perl5>;
use URI:from<Perl5>;
sub MAIN($url = 'https://phoenixtrap.com') {
my @feeds = XML::Feed.find_feeds($url);
my $feed = XML::Feed.parse( URI.new( @feeds.first ) )
or exit note "Couldn't find a feed at $url";
put .title, "\t", .link for $feed.entries;
}

It’s even closer to Perl now, though it’s using the first routine rather than subscripting the @feeds array and leaving off the the $_ variable name when calling methods on it—less punctuation noise often aids readability. I also took a suggested exit idiom from Raku developer Elizabeth Mattijsen on Reddit to simplify the contortions I was going through to exit with a simple message and error code.

There are a couple of lessons here:

  • A little more effort in module shopping pays dividends in simpler code.
  • Get feedback from far and wide to help improve your code. If it’s for work and you can’t release as open-source, make sure your code review process covers readability and maintainability.

Cover image: “Frenemies” by Mr. T in DC is licensed under CC BY-ND 2.0

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