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.
Sooner or later any programmer, writing in any language, will run across something like this Perl warning: Subroutine foo redefined. This is telling you that somehow, somewhere, you tried to create two subroutines with the same name.
Tracking this down can be tricky, and remediation equally so. The possibilities include:
If one of your own subroutines is involved, you can rename it.
If an imported subroutine that you do not need is involved, you can just not import it. This, of course, involves figuring out which imports you do need. The use of default import lists can make tracking this one down tricky.
You can use Importer to import a subroutine under a different name.
You can ignore the import mechanism and populate the symbol table yourself with something like BEGIN { require Some::Module; *foo = \&Some::Module::bar; }, after which bar() calls Some::Module::foo().
Task 1, "Disjoint Sets" was basically something I've done before somewhere else. In fact, what I'm using is overkill for just determining if two sets intersect. I imagine most people would probably use the FAQ answer. However, I'm a fan of what cardinal LanX of Perl Monks fame was trying to do in making set intersection a more "organic" operation. I don't know how much those ideas developed, however, so I'll be looking at the other solutions to see if there's anything new.
I actually did use my perlmonks code on real problem a few years ago, in modified form. It does the trick pretty quickly compared to other approaches. Thanks perl hashing!
Spoiler Alert: This weekly challenge deadline is due in a few of days from now (on Aug. 7, 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: Permuted Multiples
Write a script to find the smallest positive integer x such that x, 2x, 3x, 4x, 5x and 6x are permuted multiples of each other.
For example, the integers 125874 and 251748 are permuted multiples of each other as
251784 = 2 x 125874
and also both have the same digits but in different order.
The guilt is killing me every time I delay the monthly report. I finally found time to get this out on 22nd day of the month where I would do that on the very first day of the month in the past.
Life can be challenging at times, balancing personal and professional aspect can be difficult, I must confess.
In all of these up and down, I have to keep myself motivated and find ways to stay happy.
I try to avoid negative thoughts coming on my way and stay positive.
It’s reassuring that the list of contributors to the proposed design includes some of the most highly respected names in the Perl community, many of whom have previously taken one (or more!) tilts at this particular object-oriented windmill.
Indeed, over the past two decades I too have repeatedly attempted to design and prototype richer and more robust OO systems for Perl, starting way back in the previous millennium with a brief stint as the maintainer of Class::Struct, and continuing on though the release of modules such as Class::Std, Class::Delegation, and most recently: Dios.
One of the changes to Perl that we're considering on p5p (the perl5-porters mailing list) is the removal of taint support. The first step towards that is to add a Configure option that lets you build a Perl without taint support.
In this post I'll explain what we're considering, and why. The purpose of this post is to let everyone beyond p5p know about this, and give you a chance to comment.
Spoiler Alert: This weekly challenge deadline is due in a few of days from now (on July 31, 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: Last Sunday
Write a script to list Last Sunday of every month in the given year.
For example, for year 2022, we should get the following:
Well, "solve" may be a strong word for what I did with this problem, at least for my programming conscience. The problem statement was simple, but had no requirements for an acceptable solution other than what you could infer from the example solution in the problem statement. However I did give not one, but two solutions, so that's not totally lazy, even if each, on its own, is lazy, right?
Since my last post I wanted to take my EV charge calculator script and convert it into a web form. In this post I breakdown how I migrated the script to a Dancer2 web app.
Just a minor note for those readers who may not be aware, Dancer2 is a "lightweight web-framework for Perl" as described in Dancer2 documentation and can be similar in comparison to Ruby Sinatra and Python Flask.
I started by creating a new project folder with the dancer2 program ( # please note that I am working on a Windows PC and on a linux OS the program would just be named dancer2 )
dancer2.bat -a EVCalc
I then copy over the files inside this directory to my project repository as shown in this commit and moved all the scripts to the bin directory as shown in this commit
I wrote a script to covert the electric rate csv file into a module and added all the calculation code in the main project module. All the html markup is stored in this template file and I sprinkled some CSS which renders a page similar to the screenshot below after submitting some data for calculating the charge of an EV :
Thank you for your time, I hope you enjoyed my post.
I recently added some files for SQL 2003 and SQL 2016, created by Domingo Alvarez Duarte.
Specifically, look for:
o sql-2003-2.ebnf
o sql-2003-2.ebnf.readme
o sql-2003-2-railroad-diagrams.xhtml
o sql-2016.ebnf
o sql-2016.ebnf.readme
o sql-2016-railroad-diagrams.xhtml
I'd suggest downloading the *.xhtml files and viewing them locally, rather than hammering the on-line convertor mentioned in the readme files, which accepts *.ebnf files and displays these railroad diagrams.
And that begs the question: Is there any Perl code which converts a grammar into a railroad diagram?
Originally, the Perl Weekly Challenge called for solutions in Perl and Raku (also known as Perl 6 at the time). But, very soon, people started to provide solutions in other “guest” languages. See for example my blog post providing solutions to the task described below in about 18 different guest languages.
One of the languages I tried for the first time last week with Sylvester’s sequence is dc, and it turned out to be much more difficult and challenging than I initially thought. One of the problems is that there is only very limited documentation on this old programming language. So I thought it might be useful to describe in some details how I solved it. I provided detailed explanations in this other blog post. I’ll now do the same with the disarium number task of this week, which is a bit more complicated.
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.
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.
Spoiler Alert: This weekly challenge deadline is due in a few of days from now (on July 24, 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: Disarium Numbers
Write a script to generate first 19 Disarium Numbers.
A disarium number is an integer where the sum of each digit raised to the power of its position in the number, is equal to the number.
For example,
518 is a disarium number as (5 ** 1) + (1 ** 2) + (8 ** 3) => 5 + 1 + 512 => 518
Look, that's why there's rules, understand? So that you think before you break 'em. — Terry Pratchett, in Thief of Time.
A couple installments into this series of blog posts, I realized an introduction to Perl warnings would be appropriate, with some words on how to turn them off, and why you probably do not want to. Yes, this should have been the first post in the series, but I didn't know it would actually be a series, and, well, maybe better late than never.
The Perl compiler/interpreter can emit warnings when it finds things that may indicate a problem with the code. These are not (yet) enabled by default, but experience has shown that enabling them can highlight conceptual and logic errors.
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).
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:
