Some contents of the PerlMonks article are largely repeated here.
This piece of PerlMonks article is already 19-year-old, but it is
still valid. One of the good things of the article is that you need not
install new modules or programs if you are on a *nix system.
Prerequisites
One should have some knowledge on modules, packages and, not really necessary, object-oriented Perl ("Perl OO" in short).
The Perl compiler wants to help us write clean code. One of the ways that it does this is to issue warnings when a global variable appears ony once: Name "main::Foo" used only once: possible typo at ...
The thing is, sometimes this is not an error. For example, we may want to refer to a global variable in another package, one that was not imported into our namespace.
I have seen various expedients used to avoid this warning in CPAN code. Something like $Foo::Bar = $Foo::Bar = 42; is fairly typical. Sometimes this strange-looking code is commented as to its purpose, others not.
Alternatively, you can use the pragma no warnings 'once'; to supress this warning. This seems to me the appropriate way to spell "I meant to do that!" under the circumstances:
I'm always doing other things and then Sunday comes and I start thinking, "How much time do I have before it's midnight in London?"
When "The Perl Challenge" first started, I was happy to just ponder the problems. Then came the pandemic and I thought that I would use some of my then copious free time to contribute. Then time got not-so-copious. And more people started contributing to TWC, some people much more talented than me, it turns out.
So I'll take a stab at things when I can and I'll still try to write a stand-alone script the way (I wish) I would at work, but my threatened laxness in writing things up will be more of a promise: Light banter to cast a veneer of confidence on the correctness of my results, anything else is extra.
I explain how to create your website using Giblog and Perl by live coding. Giblog is a Perl module to create web sites. If you see this movie, you can create your web site using Giblog and Perl(although you need some Linux knowledge).
Write a script to figure out if they are disjoint.
The two sets are disjoint if they don’t have any common members.
Example:
Input: @S1 = (1, 2, 5, 3, 4)
@S2 = (4, 6, 7, 8, 9)
Output: 0 as the given two sets have common member 4.
Input: @S1 = (1, 3, 5, 7, 9)
@S2 = (0, 2, 4, 6, 8)
Output: 1 as the given two sets do not have common member.
As you all know, I have recently started taking part in the weekly challenge again. I have always complained about the lack of time doing things I always wanted to do. But then it doesn't stop me taking up new projects. I have to learn how to prioritize projects. May be one day, I will get there. Right now I am actively working on 2 new projects simultaneously. First is preparing the talk for the upcoming Raku Online Conference. It is going to be my personal journey to Raku. And the second is very close to my heart, working on my first book about Perl in association with Dave Cross.
One of the remarkable things about the
Date-Manip package is
its flexibility in the matter of input. If I mean "tomorrow noon," I do
not have to think of what today is, I simply specify "tomorrow noon," or
its equivalent in any of sixteen other languages.
One day, I thought: what about "tomorrow sunrise?" And thus was born
Date-ManipX-Almanac.
In principal, there can be support for any almanac event from any
astronomical body in the
Astro::Coord::ECI
ecosystem. In practice at least most of them are covered, though I have
not audited for 100% coverage. This includes the bodies in the
Astro-Coord-ECI-VSOP87D
distribution, should you want planets through Neptune. Pluto was not
covered by the VSOP models -- its exclusion is not a political
statement, at least not by me. Satellites are not supported, and
currently there are no plans for them.
Spoiler Alert: This weekly challenge deadline is due in a couple of days, on Independence Day (July 4, 2021). This blog post offers some solutions to this challenge, please don’t read on if you intend to complete the challenge on your own.
Task 1: Swap Nibbles
You are given a positive integer $N.
Write a script to swap the two nibbles of the binary representation of the given number and print the decimal number of the new binary representation.
A nibble is a four-bit aggregation, or half an octet.
To keep the task simple, we only allow integer less than or equal to 255.
You have 46- hours to play with it if you align with official deadline. It probably spends you 2~5 hours in this weekend. Beware! Doing the bonus part may spend you a block of extra 2 hours or more.
I wish more people will participate and show different approaches to the task. (And, may the participant give me some feedback as a puzzle creator?)
One may have advantage if s/he has played chess.
As the puzzle creator, of course I had a sketch of a solution in my mind.
Yesterday I solved (== coded) the puzzle and is blogging about it this morning. [Spoiler Alert] If you are interested in my solution... source code , blogpost
Miscellaneous:
My blog is moved to GitHub, mainly because I think soon or later I will blog on other programming languages or issues. At this moment, it has a few posts. :o)
In this time, I review constructor argument customize. BUILDARGS can customize contructer argument. It is good enough for me. I think existing library that receive hash references as argument will have a slight performance penalty because a BUILDARGS function call.
Spoiler Alert: This weekly challenge deadline is due in a couple of days (June 20, 2021). This blog post offers some solutions to this challenge, please don’t read on if you intend to complete the challenge on your own.
Task 1: Missing Row
You are given text file with rows numbered 1-15 in random order but there is a catch one row in missing in the file.
DBD::SQLite 1.67_07 (with SQLite 3.36.0) is a release candidate for the next stable DBD::SQLite. This release has a notable change to improve how to deal with Unicode/Latin-1 characters, contributed by Felipe Gasper. If you write a new application, it is recommended to use one of the newly added modes like this:
I thought I’d try out Tau Station for a couple of days and get a quick blog post out of it. That was three months and 11 levels ago. It took 2 months to wind down my obsessive nature and if not for Tau, I could have pushed a couple of new module versions to CPAN by now. That’s rather the reason that I don’t play games in the first place, so I can’t give great comparisons.
To sum up, Tau Station is a web-based, second-person adventure with resource management in real-time: a Choose-your-own-Adventure book crossed with Freeciv. Oh, and it’s free. Well, freemium, but the least obtrusive freemium game I’ve ever seen.
Spoiler Alert: This weekly challenge deadline is due in a few days from now (on August 22, 2021 at 24:00). This blog post offers some solutions to this challenge, please don’t read on if you intend to complete the challenge on your own.
Task 1: Count Numbers
You are given a positive integer $N.
Write a script to print count of numbers from 1 to $N that don’t contain digit 1.
I was just going to use a variation on last week's "Nybble Swap" task for this, but then I foolishly thought, "No, I've read Hacker's Delight I should twiddle bits!"
Okay, now that I told you about my first mistake, let me tell you, the bit twiddling was fun once it started working but I do have a little regret that it's straightforward bit-twiddling: I created a bit mask to pick out alternating bits, then just did the shifting and OR-ing you would expect to switch the even/odd bits. I can't help but wonder if there isn't some clever one-liner in Hacker's Delight. I can't claim to have remembered it even once though: I skimmed the book.
(image from wikipedia)