Spoiler Alert: This weekly challenge deadline is due in a few days from now (on December 18, 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: Special Integers
You are given a positive integer, $n > 0.
Write a script to print the count of all special integers between 1 and $n.
An integer is special when all of its digits are unique.
Example 1:
Input: $n = 15
Output: 14 as except 11 all other integers between 1 and 15 are spcial.
Example 2:
Input: $n = 35
Output: 32 as except 11, 22, 33 all others are special.
You may have seen Ovid's recent post
on his discussions with the Perl Steering Committee
about moving forward with implementing an initial subset
of the Corinna proposal in the Perl core.
One of the issues that came up during those discussions was the best way to provide private
methods in Corinna. The current Corinna proposal is that this would be done (like almost
everything else in Corinna) via an attribute:
method do_internal :private () {...}
Thereafter, the do_internal() method can only be called from within
the current class, and is never overridden by derived-class methods when
it is called within its original class.
In other words, the :private method effectively prepends the following
code to the start of the method:
croak "Can't call method 'do_internal'"
if caller ne __CLASS__;
Who knows what evil lurks in the hearts of men? The Shadow knows!
OK, Perl does not literally have a warning about a 1930's pulp fiction and radio serial character. But Perl 5.28 introduced shadow as a new warning category for cases where a variable is redeclared in the same scope. Previously, such warnings were under misc.
To tickle this it is sufficient to
$ perl -Mstrict -Mwarnings -Mdiagnostics -e 'my $x; my $x;'
If your Perl is at least 5.28.0, you get the diagnostic
I explain JavaScript supported web scraping using Perl and Selenium::Remote::Driver. Selenium::Remote::Driver is a Perl module for Selenium. Selenium provides the APIs for JavaScript supported web scraping.
Spoiler Alert: This weekly challenge deadline is due in a few days from now (on December 11, 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: Digital Clock
You are given time in the format hh:mm with one missing digit.
Write a script to find the highest digit between 0-9 that makes it valid time.
Example 1
Input: $time = '?5:00'
Output: 1
Since 05:00 and 15:00 are valid time and no other digits can fit in the missing place.
Continuing from our last post, I talked about how ANSI Game Engine is a colourful telnet server. We left off with needing to fork the engines telnet server.
Player 2 has joined the game!
Time to level up our telnet server and make it multi-player with some knify forky.
I've added in the strftime identifier from Perl's POSIX module to help with time stamping the output. The setsid identifier is for starting a new session and group ID for each forked process. A.K.A, the child process. :sys_wait_h is for returning without wait after the child process has exited, using the WNOHANG flag when calling waitpid(). This provides non-blocking wait for all pending zombie children.
In 2022, the German Perl/Raku Workshop will take place in Leipzig. We are very happy to announce that long time Perl supporter Geizhals Preisvergleich sponsor the workshop.
Spoiler Alert: This weekly challenge deadline is due in a few days from now (on December 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: Binary String
You are given an integer, $n > 0.
Write a script to find all possible binary numbers of size $n.
A casual remark about closures which I made in My Favorite Warnings: redefine touched off a long off-topic exchange with Aristotle that I thought ought to be promoted to a top-level blog entry. The big thing I learned was that any Perl subroutine can be a closure. The rest of this blog will try to make clear why I now believe this. The words are my own, as are any errors or misconceptions.
The second sentence of Wikipedia's definition of a closure says "Operationally, a closure is a record storing a function together with an environment." This makes it sound a lot like an object, and therefore of little additional interest in an O-O environment.
This blog post addresses checksum and signature verification vulnerabilities affecting CPAN, the cpan client, and the cpanm client, which were published in a security advisory on 23rd November 2021. If you're not aware of this topic, you might like to start by reading the advisory. This post gives a high-level description of the issues, what has been done to address them, what is still left to do, and what you should do. If you have any questions on this, you can add comments here, or email the PAUSE admins (modules at perl dot org).
Before we dig into the details, we'll first give an overview of how the relevant parts of the CPAN ecosystem work.
If you're not interested in the details, skip to the section "What do you need to do?"
TL;DR: make sure your CPAN client uses https and a trusted mirror – such as cpan.org
Spoiler Alert: This weekly challenge deadline is due in a few days from now (on November, 27, 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: Binary Flip
You are given a positive integer, $n.
Write a script to find the binary flip.
Example 1
Input: $n = 5
Output: 2
First find the binary equivalent of the given integer, 101.
Then flip the binary digits 0 -> 1 and 1 -> 0 and we get 010.
So Binary 010 => Decimal 2.
The deprecated warning is a grab-bag. Basically, anything that is deprecated causes this warning to be generated, and the list changes from release to release.
The only reason I can think of ever to turn this off is around a deprecated construction while you are actively working to eliminate it. Silencing it and then forgetting about it will bite you, eventually.
For the curious (and to run my word count, since otherwise this would be a really short blog entry), the current list of deprecations according to the 5.34.0 perldiag is:
David was a gentleman and a scholar: a gentle, warm, erudite, funny, clever, and deeply kind man. And one who has made a vast contribution to our Perl and Raku communities over more than quarter of a century.
My most sincere condolences to David's family...and to the countless other colleagues, acquaintances, and admirers around the world who will be mourning him today.
Like so many others, I was proud to call David my friend.
I will miss him profoundly.
Spoiler Alert: This weekly challenge deadline is due in a few days from now (on November, 20, 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: Twice Largest
You are given list of integers, @list.
Write a script to find out whether the largest item in the list is at least twice as large as each of the other items.
Why ? Because I can. More seriously I have a project where I need to inject new Snes code in a running game and I want to express directly this new code in my Raku component (A webserver service). I want to have special sub that returns me Snes bytecode but that contains Snes assembler.
I tried injecting a SLANG in Raku already. Like writing my $byte-code = SNES lda $42; sta $54; rtl; But it’s rather tricky and I will probably just have a additional Slang with its own grammar in a dedicated file.
I registered on blogs.perl.org today so that I could comment on posts about object systems. However, the very first thing I encountered was a password page with NO SSL. So, even though I have a ton to say about object systems, my first blog post will instead be about setting up SSL.
(I’m aware that this is a “legacy server problem” but I also recently learned that it doesn’t matter with traefik.)
In this grand year of 2021 you can add SSL to any site, on any architecture, for free, by adding 3 files to your server, making one small config change to Apache, and running a service. We are truly living in the future.
