Spoiler Alert: This weekly challenge deadline is due in a few days from now (on July 9, 2023, 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: Special Notes
You are given two strings, $source and $target.
Write a script to find out if using the characters (only once) from source, a target string can be created.
I have always understood that variables whose names begin with anything but an alphabetic or an underscore are reserved to Perl, and you mess with them at your peril. And this is the gist of the Porters' response to the post. Recent versions of perlvar say this explicitly, though earlier versions of that document restrict themselves to describing currently-implemented special variables.
For what it's worth, perl532delta appears not to mention this as a new diagnostic.
I wondered how much of this kind of thing was in CPAN, so I whipped up a Perl::Critic policy to try to find them: Variables::ProhibitNumericNamesWithLeadingZero. I then ran this against CPAN as it stood July 23 2022.
I will get it wrong. I will start off by saying that, not just because I am married and this sentiment has been conjugally programmed in me for years, but because doing things "my way" will not suit everybody. We approach life, programming, drawing from different perspectives, different analogies, and one method however disagreeable to one person, may be perfectly logical to another. Even our own actions and analysis show conflicts. Take a cup of tea. I drink from the top of the cup, but measure from the bottom. Take character position in programming code...we measure lines from the top, then character on that line. But when we write, we write one line at a time, populating columns in a line before going to the next line.
You are given an array representing box coins, @box.
Write a script to collect the maximum coins until you took out all boxes. If we pick box[i] then we collect the coins $box[i-1] * $box[i] * $box[i+1]. If $box[i+1] or $box[i-1] is out of bound then treat it as 1 coin.
Example 1:
Input: @box = (3, 1, 5, 8)
Output: 167
Step 1: pick box [i=1] and collected coins 3 * 1 * 5 => 15. Boxes available (3, 5, 8).
Step 2: pick box [i=1] and collected coins 3 * 5 * 8 => 120. Boxes available (3, 8).
Step 3: pick box [i=0] and collected coins 1 * 3 * 8 => 24. Boxes available (8).
Step 4: pick box [i=0] and collected coins 1 * 8 * 1 => 8. No more box available.
In the year 2000, the world was a different place. Y2K was still fresh in our memories, many of us had just partied like it was 1999 and Mark Fowler had given up eating chocolate.
Hurray, released another version of Chart without new features. Actually rewrote the complete documentation and I guess especially this page (with a little help of this list) is all what most people need. That also allowed us to drop the old PDF and HTML docs which took 8/9 of the distributions space (good side effect).
But main reason to tell this: writing the docs forced me to plough through most of code and also test most of it with self written or at least adapted code, which brought me into the position actually understand what I maintain.
So now I can give actually intelligent responses to feature requests. So please post them here or there. And yes , there will be SVG support, but not soon.
The Perl sort built-in is mostly (at least by me) called as sort LIST or sort BLOCK LIST. But there is a third way to call it: sort SUBROUTINE LIST, which actually appears first in the documentation.
This is not a blog entry about using the sort SUBROUTINE LIST form of sort. It is more about the need to be aware of this form when writing (or trying to write) the sort LIST form.
Consider the following situation: you have a subroutine foo() which returns an un-ordered list. You need that list sorted. Perl has a sort built-in, so your (or at least my) first reaction is to write my @sorted = sort foo();, run it, and then wonder why @sorted is empty.
Spoiler Alert: This weekly challenge deadline is due in a few days from now (on July 2, 2023 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: Count Primes
You are given a positive integer, $n.
Write a script to find the total count of primes less than or equal to the given integer.
Example 1
Input: $n = 10
Output: 4
Since there are 4 primes (2,3,5,7) less than or equal to 10.
So why not a generalized interface to Bug, Task, and Issue trackers? And an accompanying cli tool?
Jira is obviously very common for organizations to use, Github issues are ubiquitous, Bugzilla is still around, Request Tracker has a strong following, not to mention Zendesk, OTRS, and so many others you're forced to use each day for your work. Likely your organization or employer uses more than one!
Having a generalized interface makes automation interactions more trivial and vastly more consistent. With this interface established, an accompanying command line tool becomes a logical addition. And if you aren't yet automating interactions with your Bug / Task / Issue tracker, then having an interface is even more important to getting you started.
Such an interface would be the majority of whats needed for a unified interface and cli tool and to interact with CPAN modules bugs/issues regardless if they are on Github, RT, or other. Something similar to Debian's reportbug command.
I wrote this post after seeing Flavio Poletti's blog post entitled
OATH Toolkit.
I have been a fan of time-based one time passwords (TOTP) for many years.
In fact, I used Mobile-OTP in commercial
applications for several years before the
Initiative for Open Authentication (OATH)
and OATH/TOTP were codified in
RFC6238.
Now-a-days, OATH/TOTP is the best choice for time-based one time passwords,
and has been for at least a decade.
Introduction
I have implemented OATH/TOTP many times in my career, and in several programming
languages, including Perl. One of those Perl implementations is within the
open source program kpcli.
Using Authen::OATH for TOTP
Using Authen::OATH for TOTP is straightforward. The kpcli code
appears a little overly complex because it optionally demand-loads the
Authen::OATH module and has support for digest ciphers other than
SHA1. This is kpcli's get_totp() subroutine:
This policy is assigned to the 'bugs' theme. It has low severity because there are some uses of these operators that seem legitimate to me -- or at least I see no easy way to get around their use.
On the one hand, something like
-r $file or die "File $file not readable\n";
open my $handle, '<', $file;
is wrong several ways. On the other hand, it is hard to see how to implement File::Which without the use of -x. And in fact it does use -x.
Spoiler Alert: This weekly challenge deadline is due in a few days from now (on June 25, 2023 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: Matching Members
You are given a list of positive integers, @ints.
Write a script to find the total matching members after sorting the list increasing order.
Hello All,
Facing flock error when trying to execute the Automated unit testing .
705:041754.467 CPM0 frl-plugin:perlscript: ERROR: 'flock' trapped by operation mask at /usr/lib64/perl5/vendor_perl/Storable.pm line 268.
Compilation failed in require at /usr/share/perl5/vendor_perl/Const/Fast.pm line 15.
Compilation failed in require.
BEGIN failed--compilation aborted.
I had a great time hacking on the Perl Navigator and Raku Navigator as part of the Perl IDE Hackathon 2022. Thank you to everyone who volunteered their time in person or remotely. Thanks especially to Brian for having many github issues ready for people to work on, and for helping so many people understand the concepts of Language Servers. I received compliments that the Hackathon was very organized but truthfully if people got that impression then Brian should get all the credit!
As a community I feel we could do better at helping people getting started and involved, so my goal was to emphasize first time and one off contributions. Brian caught the vision on this and as mentioned, did a great job preparing github issues and spent much of his time getting peoples development environment running. Hopefully he will post a report on what got done in the near future.
Some of the presentations are not yet published - we need to work on
the video some more..
Again, thanks to our speakers, our sponsors and everybody else for the
great conference. Next year we'll hopefully meet again in 2023 in Frankfurt am Main in person!
Spoiler Alert: This weekly challenge deadline is due in a few days from now (on June 18, 2023 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.
Arithmetic Subsequence
You are given an array of integers, @ints.
Write a script to find the length of the longest Arithmetic Subsequence in the given array.
A subsequence is an array that can be derived from another array by deleting some or none elements without changing the order of the remaining elements.
A subsequence is arithmetic if ints[i + 1] - ints[i] are all the same value (for 0 <= i < ints.length - 1).
Moose is great, but it does introduce a slight performance hit to your code. In the more than 15 years since it was first released, hardware improvements have made this less of a problem than it once was. Even so, if performance is a concern for your project, Moose might not be what you want. It also has a fairly big collection of non-core dependencies.
Moo is a lighter weight version, minus with meta-object protocol, but supporting nearly all of Moose's other features. It loads faster, sometimes runs faster, and has fewer dependencies. (And most of the dependencies it does have are just modules which used to be part of Moo but were split out into separate distributions.)
But what if you could have fast Moose-like object-oriented code without the dependencies?
In 2013, Michael Schwern started work on Mite to do just that. It was abandoned in 2014, but I've taken it over and expanded the feature set to roughly equivalent to Moo.
Mite is an object-oriented programming compiler for Perl. It allows you to write familiar Moose-like object-oriented code, then compile that into plain Perl with zero non-core dependencies. Your compiled code does not even have a dependency on Mite itself!
Every Perl gig I have ever had, and from most of the conversations I had at this years Perl and Raku Conference, was working on a large code based that is serving the business and it's customers very well such that the business is profitable (i.e. a mature code base).
This is an enviable position to be in but whilst this software is robust from the outside, there is often a reluctance to make dramatic changes. Unfortunately code that is perceived as too fragile to touch tends to be replaced and replaced in another language.
The PPI + Class::Inspector combination is already being used by people I've spoken too, in bespoke tools to refactor large code bases reliably.
We have frameworks for testing (Test:: etc) and linting (Perl::Critic) with suites of well established reusable polices, so why not a similar framework for refactoring?
Such a tool might have provided polices to assist replacing deprecated syntax, migrate between "Try" implementations, fixing up scalar vs list context, just to name a few.
For a long time after I first encountered Perl, I looked on "list" and "array" as essentially interchangeable concepts. A list was simply the source construct corresponding to an array. This idea is mostly correct. But as they say, the devil is in the details.
One of the differences is what happens to them in scalar context. An array evaluates to the number of elements it contains. A list evaluates to its last element. So:
my @array = qw{ one two five };
say scalar @array; # prints '3'
{
no warnings 'void'; # Note the need for this
say scalar( qw{ one two five } ); # prints 'five'
}
