Recently I needed to display a map with some polygons, markers and popups on it. I wanted to have both an interactive map but also be able to create a hardcopy from my linux's terminal via a script in a headless server.

I found a solution which satisfies both requirements. Have the interactive map be from the HTML produced by LeafletJS and then spawn a headless browser (thank you WWW::Mechanize::Chrome & Corion!!) and take a screenshot of the map, via a script from any headless server.

To me, at least, the screenshot part sounds like a very roundabout way of getting a hardcopy of a map (a PDF or PNG) but after researching this for a few weeks, I realised that this is how it is done in R (and in the serpent world, it is called htmlwebshot).

Building on WWW::Mechanize::Chrome's screenshot functionality and on a conversation I had with LanX some years ago on how to inject JS into a mechanized browser and manipulate the DOM with it I have now published WWW::Mechanize::Chrome::DOMops which finds/deletes elements of the current DOM of your mechanized browser and then on top of that, WWW::Mechanize::Chrome::Webshot which takes a screenshot of your browser contents onto a local file. In short, it renders a URL or a local file onto a, possibly headless, mechanized browser (with all encompassing CSS and JS included), allows some settle time, optionally removing some DOM elements which clutter the view and takes a screenshot of what's currently rendered. I think this is as good as it gets for html2pdf. I mean the browser is the final arbiter on how html renders right? (well, sort of).

https://leafletjs.com/ is really very good at displaying map tiles, images/satellite or vectors, from various sources (e.g. OpenStreetMap for navigation vector maps or ArcGIS/ESRI for satellite images, both free). It is also very easy to draw polygons, markers, etc. on top of the map using map coordinates. And then allows you to move/pan/zoom interactively. Really cool software. Alas in Javascript.

And so, in the below script I combine both to get both a self-contained HTML (it requires lefleat.js external dependency) of an interactive map as well as a printout in the form of PDF/PNG.

Caveat: the output PDF contains only part of the view (increasing the dpi perhaps?) whereas the PNG contains everything the browser window contains. So, a PNG is output instead.

PS: I had in mind to create a Just another Perl Hacker all over Africa but the polyline is quite some bytes long and I will spare you the bandwidth. Just imagine Just another Perl Hacker sprayed all over the globe.

PS2: Geo::Leaflet does a good job at exposing the basic functionality of LeafletJS via Perl. But there are lots more features and options for your map. I propose that once you have a basic HTML map, to template it and keep adding more features there. You do not need to keep using Geo::Leaflet. Check the script's output HTML file.

# by bliako for perlmonks 21/08/2025
use Geo::Leaflet;
use FindBin;
use File::Spec;
use WWW::Mechanize::Chrome::Webshot;

my $lat = 11.1;
my $lon = 22.2;
my $outbase = 'hack';

my $map = Geo::Leaflet->new(
    id     => "myMap",
    center => [$lat, $lon],
    zoom => 3,
);
# the tiles are coming from:
$map->tileLayer(
  # navigation vector tiles
  #url => 'https://tile.openstreetmap.org/{z}/{x}/{y}.png',
  # satellite images
  url  => 'https://server.arcgisonline.com/ArcGIS/rest/services/World_
+Imagery/MapServer/tile/{z}/{y}/{x}',
  options => {
    maxZoom => 19,
    maxNativeZoom => 23,
    #attribution => 'openstreetmap',
    attribution => 'esri',
  },
);

$map->polyline(
  coordinates => [
    [9.0, 20.0],
    [11.3, 23.1],
    [12.1, 19.4],
  ], options=>{color=>'red', weight=>'5'}
);

my $map_html = $map->html;

my $outdir = $FindBin::Bin;

my $map_html_outfile = File::Spec->catfile($outdir, $outbase.'_map.htm
+l');
my $FH;
open($FH, '>', $map_html_outfile)
    or die "failed to open file for writing html '$map_html_outfile', 
+$!";
print $FH $map->html;
close $FH;

my $map_pdf_outfile = File::Spec->catfile($outdir, $outbase.'_map.png'
+);

my $shooter = WWW::Mechanize::Chrome::Webshot->new({
  'settle-time' => 10,
  'resolution' => '2000x2000',
});

my $local_uri = URI->new('file://'.$map_html_outfile);

$shooter->shoot({
    'output-filename' => $map_pdf_outfile,
    'url' => $local_uri->as_string,
    'remove-DOM-elements' => [
      {'element-xpathselector' => '//div[id="leaflet-control-container
+"]'},
    ],
    'exif' => {'created' => 'by the shooter'},
});

print "$0 : done, map saved to PDF '$map_pdf_outfile'\n";
[download]

bw, bliako

• reverse
https://github.com/Perl/perl5/issues/20692
• lc, uc, fc
http://0x80.pl/notesen/2025-02-02-utf32-change-case.html
• index, rindex
http://0x80.pl/notesen/2016-11-28-simd-strfind.html
• eq, ne
https://www.strchr.com/strcmp_and_strlen_using_sse_4.2
• tr, quotemeta
https://github.com/lemire/despacer
• split ' '
• join
• sort

• Encode
https://github.com/simdutf/simdutf
• Digest::MD5
• Digest::SHA
https://github.com/minio/sha256-simd
https://github.com/qinwang/cryptopp/blob/master/sha-simd.cpp
• File::Compare
• MIME::Base64
http://0x80.pl/notesen/2016-09-17-avx512-foundation-base64.html
https://github.com/simdutf/simdutf?tab=readme-ov-file#base64
• Unicode::Normalize

• pack/unpack
• regex, split //
https://github.com/intel/hyperscan
https://github.com/VectorCamp/vectorscan

ikegami recently posted a question that eventually led me to the new perlclass documentation.

I haven't been following along that much, but it seems intriguing.

I have a ton of OOP code using the old-school bless() way of doing things, and after a cursory look at this documentation, my gut says that I shouldn't change anything. There have been so many iterations of OOP modules and such, it just seems that it'll keep changing over and over again. However, with that said, I've been around a long time, and considering almost all of my code will still run on 5.8, Perl is known for its backward-compatibility.

What are your thoughts on this new way of Perl OOP development? Are you embracing it? Are you sticking with the old? For long-time developers, are you considering transitioning?

Legitimately curious,

-stevieb

Video: Yet Another Program on Closures ~ Steven Lembark ~ TPRC 2025 - YouTube"

Recordings from YAPC::NA::2025 aka The Perl and Raku Conference June 27-29 2025 in Greenville, SC, USA

Posted here one by one for promotion and feedback.

Homepage: "Closing in on an Application: Applying Closures with Perl and Raku"

Abstract:

Video: "Perl and the Unix Philosophy ~ David Both ~ TPRC 2025 - YouTube"

Recordings from YAPC::NA::2025 aka The Perl and Raku Conference June 27-29 2025 in Greenville, SC, USA

Posted here one by one for promotion and feedback.

Homepage: "Our Keynote Speaker"

Abstract:

Hello worthy Monks and Nuns. I'm writing today because on Saturday (a couple days ago) I had a personal triumph: I got the tool distcc working across my LAN; at present providing support to a laptop running Linux from a desktop also running Linux. The speed-up in intensive compilations of some Perl extension modules is noticeable, for example, in building modules in the the Digest:: namespace, particularly with one module (I don't recall for sure which one) which had dozens of XS files to convert to C and compile.

I had distcc set up on my client machine (the laptop) months ago, at that time having made the little farm of symlinks recommended as the way to drive distcc in turn to drive gcc. What I didn't have working and couldn't get a handle on was the setup on the host(s), where the compilation is performed; in the file /etc/distcc/clients.allow I needed to define client hostname specifications in CIDR notation (for me, 192.168.1.0/24) for "allowed clients." Without that set up right, I kept seeing messages from distcc saying connection refused or variants on that.

Obviously big jobs like building the Linux kernel or Samba are where having something like distcc is really helpful. But it's just plain cool to have it working for Perl tasks too.

    Soren

As many of you know nowadays I'm not programming for my work since years. In the not so recent past I've made some stuff for my pure pleasure or just to help a bit here.

The programming communtiy did not cried for this :)

At work I suffered a fistfull of company mergeS and now I'm relegated to boring tasks as boring can be to renew SSL certificates.

Our IT world runs as a mad without a precise destination and strange things happens, as it happened that CA/Browser Forum decided to reduce SSL certificate duration in this way:

• after March 15 2026: validity reduced to 200 days
• after March 15 2027: validity reduced to 100 days
• after March 15 2029: validity reduced to 47 days <--- O_O

For sure bosses will complain with: "hey, we have a Dev Dpt here" ..but they act at geological times, and if they insist I can at least propose to setup a demo or better the core functionality we'd like to have distilled into a Perl module (a group of..). This point is important.

I cant let this small chance to fade out, so I must be prepared ( dormitare de fuga cogitante vetat ).

Nowadays Macaroni Group uses Digicert for almost all SSL certificates. They have some APIs for their CertCentral (the new, shiny, fancy, fashion web interface). I asked to tech support if they have also a SandBox environment (money is involved) and they didnt even know the term.. :(

So here I'm, after this long rant, to ask you how to plan my strategy in the right way.

• A base module to use automation-api let say Digicert::Automation. Maybe there is the need to have a base module for the general API: service-apis Ideally this module should be public even if I already fear the testing part.
• A serie of other modules using the above, private to the company I work for, to manage: customers, contacts, mail, orders info e renewals etc.
• a small DB to record customers, their certificates, contact informations, internal contact.. I'd like to keep this as small as possible, ideally an SQLite one.
• a CLI tool to inspect orders, renew certificates etc.. using the above modules and DB.
• ?? a web interface? I'd skip this part, but it depends how bosses see it.
• a cron job to run daily using the above CLI to monitor orders and automatically renew expiring ones.

What I'd like from your part at the moment are: suggestion on the big picture, its design implementation, on hoW to start coding the base module, previous experience in this.. and whatever you think is important to take in count.

Hopefully this is the first of many request on the matter.

L*

The Guardian asked in a recent Monday puzzle for an optimal strategy to find the smallest and the biggest in a deck of 100 cards.

https://www.theguardian.com/science/2025/may/12/can-you-solve-it-are-you-craftier-than-a-cat-burglar

(It's not the rope riddle)

While my strategy was optimal like the proposed solution, they claimed the formal proof that there can't be any better solution to be "too technical" to be published there. (Pierre de Fermat giggles in his tomb).

The attempts in the comment section didn't impress me either.

Anyway I spent the last hours figuring out an elegant proof for a general formula of any numbers of cards.

But the comment section there is long closed and I thought the local crowd here would like to try their best too ...:)

So here the task again: (copied from above link)

¹) It's quite rich to ask for an optimal strategy without presenting one...

I sit on a Program Advisory Committee for a local college as an industry representative, and at next week's meeting we're going to be asked about 'AI in the workforce'. They'll be asking about specific areas, a) How organizations are integrating AI tools, b) Whether AI can be used as a supplement or replacement, and c) What implications AI has for productivity and skill sets.

What do you think college graduates should know about AI? How much do you think they should rely on AI tools? Is vibe coding a real thing?

About two years ago, Veritasium posted The Riddle That Seems Impossible Even If You Know The Answer on Youtube. Today i was rewatching that video, because after seeing it initially i had some doubts, and it was a bit of an itch i finally decided to scratch.

The basic riddle goes something like this (watch the video for a much more coherent explanation AND the solution):

1. You have 100 prisoners, each with a number.
2. There is a room with 100 (numbered) boxes, and every prisoner number is in one random box.
3. Prisoners enter the room one by one
4. Each prisoner can open 50 boxes and search for their prisoner number.
5. Each prisoner has to leave the room exactly as he found it.
6. If ALL prisoners find their own number, everyone goes free.
7. If even a single prisoner fails to finds his number, everyone stays in jail.
8. Prisoners can decide on a tactic BEFORE the event, but can't communicate in any way DURIN the event.

If prisoners just do random sampling, their chances are 0.5**100 = 0.0000000000000000000000000000008.

Is there a better tactic? (Rest of the post in spoiler tags if you want to have a go on the problem yourself).

Frankly, even having programmed a full simulation of the solution myself, it still absolutely boggles my mind that this actually works at all. Maths is weird.

Brothers and sisters, fellow Monks (lend me your ears),

I have recently discovered that there is still quite a lot of hope for using a smartphone as a tool for empowering people and not enterprises. Android is providing a very potent program: the Android Debug Bridge (ADB) which communicates with an Android device connected to your desktop (via USB or in same wifi network). With this program, one can tell the device to wake up, to enter the passcode of the screensaver, to navigate to the home screen, to open apps, to close apps, to swipe, to click, to input text. To get readings from sensors, to get a screenshot or a screenvideo and finally to dump the current screen's UI as XML which can then be parsed to find widgets of interest, e.g. a button to click, a textbox to enter text, a list of contacts, etc.

The two main problems with controlling your smart device in such a way are: 1) Android API differences between versions, so standard apps or widgets are named differently. 2) Android remembers to notify you about something when in the middle of controlling an app and steals the focus. But neither of these problems is insurmountable.

The idea of controlling a device from my desktop is very appealing. In fact, I do not use a real device but an emulator (A note of warning here, better use an emulator or an unimportant phone).

At first a friend wanted to keep tapping on an app in order to gain some points for an idiotic competition. Then I wanted to send viber and skype messages from the command line of my linux terminal. And so I have set out to make a thin wrapper to the ADB for Perl. There are a lot of such wrappers for a lot of environments but I did not see one for Perl yet. So here it is : Android::ElectricSheep::Automator

   use Android::ElectricSheep::Automator;
   my $mother = Android::ElectricSheep::Automator->new({
     'configfile' => $configfile,
     'verbosity' => 1,
     # we already have a device connected and ready to control
     'device-is-connected' => 1,
   });
   $mother->tap({position=>[1,2]});

   use Android::ElectricSheep::Automator::Plugins::Viber;
   my $vib = Android::ElectricSheep::Automator::Plugins::Viber->new({
   configfile=>'config/plugins/viber.conf', 'device-is-connected' => 1
+});
   $vib->open_viber_app();
   $vib->send_message({recipient=>'My Notes', message=>'hello%sMonkees
+'});
   $vib->close_viber_app();
[download]

bw, bliako

And of course, I know, you could do read_file() into $string and then eval($string) but that's not what I mean. LOL

Has Perl ever been reproduced in Perl?

Hello erudite Monks and Nuns,

I found a CPAN module recently that really makes me happy. As a habitual serial installer of anything from the CPAN that looks interesting, I sometimes forget what I have installed before I can start to write some code using it. Enter Module::List; which showed up as "recent" on MetaCPAN with the release of version 0.004. There is also a close relative, let's call it a talented nephew, Module::List::WithPath, which is based on Module::List and adds the ability to discover the filesystem path location of each module found. At the time of this writing, module Module::List::WithPath is at version 0.003002.

But we're ahead of ourselves. What Module::List does is a lookup on the prefix given as an argument to the sole subroutine in the module, list_modules, returning differing information depending on the options given (as an anonymous hash) -- for example, all the installed module names with that prefix (I won't describe every bit of the functionality or API since that's all right there on MetaCPAN for the reader to peruse). I'll make the observation that the API is a bit unusual: instead of providing a separate subroutine (either exported or not) for each kind of data sought, the module provides options (as just described above). The most interesting option (imho) is the first listed in the POD, list_modules. The return data is a hash reference with keys corresponding to module names found in the abstract namespace (regardless of where the modules were found on the filesystem). The values of the hash elements are in each case the empty string. In the case of the talented nephew, Module::List::WithPath, the element values are, instead, the filesystem locations of the modules found. Very nifty.

I just find these modules really neat and they fill a gap that I've been feeling for a long time. Quirks (arguably) of implementation aside, the modules have enabled me to write simple short scripts to query my Perl installation and discover what has lain there, waiting but forgotten.

I have a script that builds an HTML document and sends it out as an E-Mail. The problem we were seeing was that Outlook (Microsoft's E-Mail reader application) was having problems displaying the HTML document, while the raw document looked fine when I viewed it in my browser. Within Outlook, the HTML would render fine for a while, then it would drop down into showing the raw HTML, then go back to rendering the page. It was irritating.

I was using a template to generate the HTML document, so the tags were all matched: a starting and ending table tag, within that, a bunch of paired tr tags, and within each row, paired td or th tags. I've been generating tables in HTML since the late 90's, so I'm pretty sure that's right. The only new thing I've added is using styles that are defined in the page header.

Anyway, a new employee on the client team put my vanilla HTML into ChatGPT to see if it could identify what the problem was. ChatGPT listed six problems:

1. Invalid table headers - except they were all matched, and contained within a tr element;
2. CSS issues - telling me that border-collapse: collapse would be better than border-collapse: separate; - irrelevant;
3. Missing closing th tags - same error as #1. All tags were matched;
4. Potentially Incorrect Data Formatting - suggesting that <td class='left'>0</td> would be better displayed as <td class='left'>0.00</td>, which was irrelevant;
5. Incorrect HTML Tag Nesting (Semantics Issue) - this was reporting that a style was declared in the page header but never used, irrelevant; and
6. Email Signature Formatting - some discussion about how the confidentiality statement was too wordy.

Oh.

Oh no. Really?

Finally, at 8pm last night, I realized what the problem was. Blank lines. Outlook doesn't like blank lines within an HTML document. It interprets that as the end of the document, and goes back to showing raw text. Until the HTML starts up again, at which point (for some special, lucky, magic, Microsoft reasons) it goes back to showing the interpreted HTML. Oh, Microsoft.

ChatGPT didn't pick up on the blank lines, instead, it picked up on a bunch of inconsequential or irrelevant issues with the HTML.

So, I'm still a little suspicious of AI in general. It's not yet at the point where it can make creative leaps; it still wants to examine each grain of sand on the beach, rather than look at the shape of the dune. Sure, maybe ChatGPT should have been specifically prompted with 'Outlook isn't rendering this HTML document correctly, tell me why' -- but I think you can get better mileage by Telling It To The Bear, or having another pair of eyes looking at the problem.

In perl.perl5.porters, Philippe Bruhat wrote:

I'm very sorry to be the bearer of sad news, which I just learned
from a co-worker who was in regularl contact with Zefram.

He forwarded me this:
We are sad to announce that Zefram (Andrew Main) died yesterday
(2025-03-10) after being hit by a train. Further details are not yet
available. Everyone close to him is very shocked by this and contact
details and further arrangements will be announced in future.
He was a long-time and prolific contributor to Perl core and CPAN,
and he will be missed.

I will forward further details (memorial or place to send condolences)
as I receive them.

Christian Walde then followed up with:

Thanks for bearing the news BooK, even if it is sad news.

As an additional bit of info, his personal website's section on this 
matter is relevant: https://www.fysh.org/~zefram/personal/death