Perl has various ways to transfer control out of the normal flow: die(), goto(), return(), next, last, and redo are among the sorts of things I mean. Not all of these are suitable for all circumstances, and Perl issues an exiting warning for unsuitable cases.

Sometimes, though, you just need to do something unsuitable. When I write an interactive script, it generally dispatches to a subroutine named after the function, something like so:

Object::Pad Yuki Kimoto's 2021-08-25(I fix this entry because default internal data structure is array reference, not hash reference).

This time is default internal data structure of the object.

Default internal data structure of the Object::Pad is array reference.

These are some answers to the Week 180 of the Perl Weekly Challenge organized by Mohammad S. Anwar.

Spoiler Alert: This weekly challenge deadline is due in a few of days from now (on Sept. 4, 2022 at 23:59). 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: First Unique Character

You are given a string, $s.

Write a script to find out the first unique character in the given string and print its index (0-based).

Example 1

Input: $s = "Perl Weekly Challenge"
Output: 0 as 'P' is the first unique character

Example 2

Input: $s = "Long Live Perl"
Output: 1 as 'o' is the first unique character

First Unique Character in Raku

JIT blogging

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.

TWC Task #1, Ugly Numbers

Higher Order Perl, Chapter 6, "Infinite Streams," Section 6.4, "The Hamming Problem"

My blog post My Favorite Warnings: redundant and missing touched on the use of the if module. Comments on that post made me think it deserved a top-level treatment, expanding on (though not necessarily improving on) Aristotle's comment.

The if module is a way to conditionally load another module and call its import() or unimport() method. Sample usages are

use if CONDITION, MODULE, ...; # load and import
no if CONDITION, MODULE, ...;  # load and unimport

In actual use the CONDITION is an expression that is evaluated at compile time. If that expression is true the named module will be loaded and its import() or unimport() method called with whatever arguments were specified. If the condition is false, nothing is done. If MODULE is a string literal it will have to be quoted, since as far as Perl is concerned it is just another argument.

It's very slow if you have more than a few thousand keys in memcached. Not an unusual use case I think? I've got a fix here, which appears to DTRT: https://rt.cpan.org/Ticket/Display.html?id=138133. Maybe? I didn't spend too long looking at memcached's low level wire protocol.

The patch passes all the module's current tests and works for us. It took our CPU load from being pegged at 75% all of the time to being idle. So, if you're using Cache::Memcached, and the ->stats method (which isn't in the XS version of the module) then you might want this patch.

On that note - who is maintaining Cache::Memcached? The last release was in 2012. This isn't a high river module, but any app of significant size or age is *probably* using it and if they're using the ->stats method then ... Sure there's the ::Fast version, but I suspect this version is in a lot of places.

So if you know someone who knows someone who can prod the current maintainers then please point them at this post/patch. If you're using Cache::Memcached then perhaps try out this patch as well.

Today I have wandered on the famous academic paper archive and suddenly a thought popped into my mind - use Perl as the keyword in searching.

Computer science papers with "Perl" in the title
https://arxiv.org/search/advanced?advanced=1&terms-0-operator=AND&terms-0-term=Perl&terms-0-field=title&classification-computer_science=y (8*)

Computer science papers with "Lisp" in the title
https://arxiv.org/search/advanced?advanced=1&terms-0-operator=AND&terms-0-term=Lisp&terms-0-field=title&classification-computer_science=y (12**)

Computer science papers with "Ruby" in the title
https://arxiv.org/search/advanced?advanced=1&terms-0-operator=AND&terms-0-term=Ruby&terms-0-field=title&classification-computer_science=y (6***)

Computer science papers with "Julia" in the title
https://arxiv.org/search/advanced?advanced=&terms-0-term=Julia&terms-0-field=title&classification-computer_science=y (53 ****)

For Haskell: ~50

For Java: ~249

For Python: ~357

For Perl Data Language (PDL): 0

Released Giblog 2.0. GIblog is a tool to create your web site easily.

Giblog 2.0 Release Announcement

Giblog 2.0 is released at 2021-7-24. serve command and publish command is added.

Giblog 2.0 Release Announcement

Giblog Document

Giblog Document in CPAN.

Giblog Document

Giblog Movie

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).

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:

These are some answers to the Week 122 of the Perl Weekly Challenge organized by Mohammad S. Anwar.

Spoiler Alert: This weekly challenge deadline is due in a few days, on July 25, 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: Average of Stream

You are given a stream of numbers, @N.

Write a script to print the average of the stream at every point.

Example:

Input: @N = (10, 20, 30, 40, 50, 60, 70, 80, 90, ...)
Output:      10, 15, 20, 25, 30, 35, 40, 45, 50, ...

Average of first number is 10.
Average of first 2 numbers (10+20)/2 = 15
Average of first 3 numbers (10+20+30)/3 = 20
Average of first 4 numbers (10+20+30+40)/4 = 25 and so on.

Have a look at the CPAN Testers reports for two TRIAL releases of the same module, one from 2 days ago, the other a little over 3 years ago:

• Matrix for Text-Tabs+Wrap 2021.0712-TRIAL

• Matrix for Text-Tabs+Wrap 2018.0419-TRIAL

  Note: the current version of Perl in late April 2018 was 5.26.2, so all reports on more recent perls came in (long) after the initial testing which I’m interested here. The relevant part of the page is therefore the part from 5.26.2 on down.

Last time, reports started coming in within hours of the release; over 60% of the picture was there within a day; some 85% after 2 days; and the first wave of reports lasted a week.

This time, it took almost a day to even start getting reports, and the diversity has been much lower. 3 days in, reports are still absent for many platforms:

• Object::Pad review Yuki Kimoto's 2021-08-21 - Constructor default argument

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.

Point->new($x, $y)

TWC Task #1, Swap Odd/Even bits

jaredor submission for Task #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.

These are some answers to the Week 179 of the Perl Weekly Challenge organized by Mohammad S. Anwar.

Spoiler Alert: This weekly challenge deadline is due in a few of days from now (on Aug. 28, 2022 at 23:59). 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: Ordinal Number Spelling

You are given a positive number, $n.

Write a script to spell the ordinal number.

For example,

11 => eleventh
62 => sixty-second
99 => ninety-ninth

Hum, this task is not very interesting, since it has more to do with English than with computer science. I’m not going to enumerate dozens of numeral or ordinal English names. So, contrary to what I usually do, I’ll use an off-the-shelf module to complete this task.

Ordinal Number Spelling in Raku

An updated but yet to be completed version is here.

So, accumulating effort from Wednesday, today(Friday) I become a CPAN contributor!

I got a PAUSE ID 2 weeks ago. If you are also interested in the Perl ecosystem, you may consider to apply for a PAUSE ID as well.

In this blogpost, I mainly follow the instructions here:

• How to make a CPAN Module Distribution, by tachyon, PerlMonks, Apr 14, 2002.

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).

In which Raku solutions give shape to Perl solutions, and vice versa, and then Raku does what Raku does best.

Task 1: Swap Nibbles - basic and extended solutions in Raku and Perl.

Task 2: Sequence of symbols 123 without adjacent 1’s. Solutions in Raku and Perl, then a radically different approach that I would have never discovered in anything but Raku.

TWC Task #1, Swap Nibbles

jaredor submission for Task #1

Hello everyone, I'm back after a year's absence, good to see everything is going as strong as ever. I have some extra time this weekend, so thought I'd try my hand at an answer again.

But, oh golly, looking back over my earlier posts on earlier problems was just painful--too many details! Going forward I'll just broad-brush things (and I mean it this time). If anyone has a question about details, then ask about them in the comments.

The swap nibbles problem is equivalent to a "swap hex-chars problem" and since we have the bigint module then any hex string can be represented by an integer. When a little investigation brought up that every bigint object has an as_hex() method, I found the restriction to positive integers less than 255 too restrictive: I decided to do them all! (Well, not quite all, since there are an infinite number of integers, but you know what I mean.)

These are some answers to the Week 177 of the Perl Weekly Challenge organized by Mohammad S. Anwar.

Spoiler Alert: This weekly challenge deadline is due in a few of days from now (on Aug. 14, 2022 at 23:59). 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: Damm Algorithm

You are given a positive number, $n.

Write a script to validate the given number against the included check digit.

Please checkout the wikipedia page for information.

Example 1

Input: $n = 5724
Output: 1 as it is valid number

Example 2

Input: $n = 5727
Output: 0 as it is invalid number

The algorithm is a check digit algorithm named after H. Michael Damm, who presented it in 2004.

Never been so busy ...

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.