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 for 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 $feed->entries;
And here’s the Raku version:
#!/usr/bin/env raku
use XML::Feed:from<Perl5>;
use URI:from<Perl5>;
sub MAIN($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.
5 thoughts on “Frenemies part 2: What a difference a (Perl) module makes”
[…] Frenemies part 2: What a difference a (Perl) module makes […]
I am chuckling at the pic.
For short programs with no other subroutines, I prefer using unit sub MAIN(signature here);, which treats the entire file as the body of the MAIN subroutine and saves you some curlies and an indentation level while still getting you the automatic argument parsing that comes from declaring a MAIN sub.
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Please try again.","receipt_payee":"Paid to","receipt_statement_descriptor":"This will show up on your statement as","receipt_date":"Date","receipt_transaction_id":"Transaction ID","receipt_transaction_amount":"Amount","refund_payer":"Refund from","login":"Log in to manage your payments","manage_payments":"Manage Payments","transactions_title":"Your Transactions","transaction_title":"Transaction Receipt","transaction_period":"Plan Period","arrangements_title":"Your Plans","arrangement_title":"Manage Plan","arrangement_details":"Plan Details","arrangement_id_title":"Plan ID","arrangement_payment_method_title":"Payment Method","arrangement_amount_title":"Plan Amount","arrangement_renewal_title":"Next renewal date","arrangement_action_cancel":"Cancel Plan","arrangement_action_cant_cancel":"Cancelling is currently not available.","arrangement_action_cancel_double":"Are you sure you'd like to cancel?","arrangement_cancelling":"Cancelling Plan...","arrangement_cancelled":"Plan Cancelled","arrangement_failed_to_cancel":"Failed to cancel plan","back_to_plans":"\u2190 Back to Plans","update_payment_method_verb":"Update","sca_auth_description":"Your have a pending renewal payment which requires authorization.","sca_auth_verb":"Authorize renewal payment","sca_authing_verb":"Authorizing payment","sca_authed_verb":"Payment successfully authorized!","sca_auth_failed":"Unable to authorize! Please try again.","login_button_text":"Log in","login_form_has_an_error":"Please check and fix the errors above","uppercase_search":"Search","lowercase_search":"search","uppercase_page":"Page","lowercase_page":"page","uppercase_items":"Items","lowercase_items":"items","uppercase_per":"Per","lowercase_per":"per","uppercase_of":"Of","lowercase_of":"of","back":"Back to plans","zip_code_placeholder":"Zip\/Postal Code","download_file_button_text":"Download File","input_field_instructions":{"tip_amount":{"placeholder_text":"How much would you like to tip?","initial":{"instruction_type":"normal","instruction_message":"How much would you like to tip? Choose any currency."},"empty":{"instruction_type":"error","instruction_message":"How much would you like to tip? Choose any currency."},"invalid_curency":{"instruction_type":"error","instruction_message":"Please choose a valid currency."}},"recurring":{"placeholder_text":"Recurring","initial":{"instruction_type":"normal","instruction_message":"How often would you like to give this?"},"success":{"instruction_type":"success","instruction_message":"How often would you like to give this?"},"empty":{"instruction_type":"error","instruction_message":"How often would you like to give this?"}},"name":{"placeholder_text":"Name on Credit Card","initial":{"instruction_type":"normal","instruction_message":"What is the name on your credit card?"},"success":{"instruction_type":"success","instruction_message":"Enter the name on your card."},"empty":{"instruction_type":"error","instruction_message":"Please enter the name on your card."}},"privacy_policy":{"terms_title":"Terms and conditions","terms_body":null,"terms_show_text":"View Terms","terms_hide_text":"Hide Terms","initial":{"instruction_type":"normal","instruction_message":"I agree to the terms."},"unchecked":{"instruction_type":"error","instruction_message":"Please agree to the terms."},"checked":{"instruction_type":"success","instruction_message":"I agree to the terms."}},"email":{"placeholder_text":"Your email address","initial":{"instruction_type":"normal","instruction_message":"What is your email address?"},"success":{"instruction_type":"success","instruction_message":"Enter your email address"},"blank":{"instruction_type":"error","instruction_message":"Enter your email address"},"not_an_email_address":{"instruction_type":"error","instruction_message":"Make sure you have entered a valid email address"}},"note_with_tip":{"placeholder_text":"Your note here...","initial":{"instruction_type":"normal","instruction_message":"Attach a note to your tip (optional)"},"empty":{"instruction_type":"normal","instruction_message":"Attach a note to your tip (optional)"},"not_empty_initial":{"instruction_type":"normal","instruction_message":"Attach a note to your tip (optional)"},"saving":{"instruction_type":"normal","instruction_message":"Saving note..."},"success":{"instruction_type":"success","instruction_message":"Note successfully saved!"},"error":{"instruction_type":"error","instruction_message":"Unable to save note note at this time. Please try again."}},"email_for_login_code":{"placeholder_text":"Your email address","initial":{"instruction_type":"normal","instruction_message":"Enter your email to log in."},"success":{"instruction_type":"success","instruction_message":"Enter your email to log in."},"blank":{"instruction_type":"error","instruction_message":"Enter your email to log in."},"empty":{"instruction_type":"error","instruction_message":"Enter your email to log in."}},"login_code":{"initial":{"instruction_type":"normal","instruction_message":"Check your email and enter the login code."},"success":{"instruction_type":"success","instruction_message":"Check your email and enter the login code."},"blank":{"instruction_type":"error","instruction_message":"Check your email and enter the login code."},"empty":{"instruction_type":"error","instruction_message":"Check your email and enter the login code."}},"stripe_all_in_one":{"initial":{"instruction_type":"normal","instruction_message":"Enter your credit card details here."},"empty":{"instruction_type":"error","instruction_message":"Enter your credit card details here."},"success":{"instruction_type":"normal","instruction_message":"Enter your credit card details here."},"invalid_number":{"instruction_type":"error","instruction_message":"The card number is not a valid credit card number."},"invalid_expiry_month":{"instruction_type":"error","instruction_message":"The card's expiration month is invalid."},"invalid_expiry_year":{"instruction_type":"error","instruction_message":"The card's expiration year is invalid."},"invalid_cvc":{"instruction_type":"error","instruction_message":"The card's security code is invalid."},"incorrect_number":{"instruction_type":"error","instruction_message":"The card number is incorrect."},"incomplete_number":{"instruction_type":"error","instruction_message":"The card number is incomplete."},"incomplete_cvc":{"instruction_type":"error","instruction_message":"The card's security code is incomplete."},"incomplete_expiry":{"instruction_type":"error","instruction_message":"The card's expiration date is incomplete."},"incomplete_zip":{"instruction_type":"error","instruction_message":"The card's zip code is incomplete."},"expired_card":{"instruction_type":"error","instruction_message":"The card has expired."},"incorrect_cvc":{"instruction_type":"error","instruction_message":"The card's security code is incorrect."},"incorrect_zip":{"instruction_type":"error","instruction_message":"The card's zip code failed validation."},"invalid_expiry_year_past":{"instruction_type":"error","instruction_message":"The card's expiration year is in the past"},"card_declined":{"instruction_type":"error","instruction_message":"The card was declined."},"missing":{"instruction_type":"error","instruction_message":"There is no card on a customer that is being charged."},"processing_error":{"instruction_type":"error","instruction_message":"An error occurred while processing the card."},"invalid_request_error":{"instruction_type":"error","instruction_message":"Unable to process this payment, please try again or use alternative method."},"invalid_sofort_country":{"instruction_type":"error","instruction_message":"The billing country is not accepted by SOFORT. Please try another country."}}}},"fetched_oembed_html":false}
[…] Frenemies part 2: What a difference a (Perl) module makes […]
I am chuckling at the pic.
For short programs with no other subroutines, I prefer using
unit sub MAIN(signature here);
, which treats the entire file as the body of the MAIN subroutine and saves you some curlies and an indentation level while still getting you the automatic argument parsing that comes from declaring a MAIN sub.unit sub
is not documented underunit
. It is, however, under “Command line interface”. 🙁@natalie #Perl to #RakuLang isn’t necessarily an “upgrade,” it’s a port to a different ecosystem and language with some similarities.I did a pair of blog posts last year showing how you could start with a small bit of Perl code and then rewrite some of it in Raku while still using Perl CPAN modules:• https://phoenixtrap.com/2021/08/17/perl-raku-best-frenemies/• https://phoenixtrap.com/2021/08/24/frenemies-part-2-what-a-difference-a-perl-module-makes/
perl
rakulang
Perl & Raku: Best frenemies—The Phoenix Trap