Beginners Perl Tutorial

A few weeks ago I got an interesting email from someone at Udemy. They were looking for someone to write a beginners Perl tutorial that they would make available for free on their web site. I think I wasn’t the only person that they got in touch with but, after a brief email conversation, they asked me to go ahead and write it.

It turned out to be harder that I thought it would be. I expected that I could write about 6,000 words over a weekend. In the end it took two weekends and it stretched to over 8,000 words. The problem is not in the writing, it’s in deciding what to omit. I’m sure that if you read it you’ll find absolutely essential topics that I haven’t included – but I wonder what you would have dropped to make room for them.

But eventually I finished it, delivered it to them (along with an invoice – hurrah!) and waited to hear that they had published it.

Yesterday I heard that it was online. Not from Udemy (they had forgotten to tell me that it was published two weeks ago) but from a friend.

Unfortunately, some gremlins had crept in at some point during their publication pipeline. Some weird character substitutions had taken place (which had disastrous consequences for some of the Perl code examples) and a large number of paragraph breaks had vanished. But I reported those all to Udemy yesterday and I see they have all been fixed overnight.

So finally I can share the tutorial with you. Please feel free to share it with people who might find it useful.

Although it’s 8,000 words long, it really only scratches the surface of the language. Udemy have added a link to one of their existing Perl courses, but unfortunately it’s not a very good Perl course (Udemy don’t seem to have any very good Perl courses). I understand why they have done that (that is, after all, the whole point of commissioning this tutorial – to drive more people to pay for Perl courses on tutorial) but it’s a shame that there isn’t anything of higher quality available.

So there’s an obvious hole in Udemy’s offerings. They don’t have a high quality Perl course. That might be a hole that I try to fill when I next get some free time.

Unless any other Perl trainers want to beat me to it.

Oh, and please let me know what you think of the tutorial.

Driving a Business with Perl

I’ve been a freelance programmer for over twenty years. One really important part of the job is getting paid for the work I do. Back in 1995 when I started out there wasn’t all of the accounting software available that you get now and (if I recall correctly) the little that was available was all pretty expensive stuff.

At some point I thought to myself “I don’t need to buy one of these expensive systems, I’ll write something myself”. So I sat down and sketched out a database schema and wrote a few Perl programs to insert data about the work I had done and generate invoices from that data.

I don’t remember much about the early versions. I do remember coming to the conclusion that the easiest way to generate PDFs of the invoices was using LaTex and then wasting a lot of time trying to bend LaTeX to my will. I got something that looked vaguely ok eventually, but it was always incredibly painful if I ever needed to edit it in any way. These days, I use wkhtmltopdf and my life is far easier. I understand HTML and CSS in a way that I will never understand LaTeX.

Why am I telling you this, twenty years after I started using this code? Well, during this last week, I finally decided it was time to put the code on Github. There were two reasons for this. Firstly, I thought that it might be useful for other people. And secondly, I’m ashamed to admit that this is the first time that the code has ever been put under any kind of version control (and, yes, this is an embarrassing case of “do as I say, not as I do“). I have no excuses. The software I used to drive my business was in a few files on a single hard drive. Files that I was hacking away at with gay abandon when I thought they needed changing. I am a terrible role model.

Other than all the obvious reasons, I’m sad that it wasn’t in version control as it would have been interesting to trace the evolution of the software over the last twenty years. For example, the database access started as raw DBI, spent a brief time using Class::DBI and at some point all got moved to DBIx::Class. It’s likely that I wasn’t using the Template Toolkit when I started – but I can’t remember what I was using in its place.

Anyway, the code is there now. I don’t give any guarantees for its quality, but it does the job for me. Let me know if you find any of it interesting or useful (or, even, laughable).

p.s. An interesting side effect of putting it under (public) version control – since I uploaded it to Github I have been constantly tweaking it. The potential embarrassment of having my code available for anyone to see means that I’ve made more improvements to it in the last week that I have in the previous five years. I’m even considering replacing all the command line programs with a Dancer app.

p.p.s. I actually use FreeAgent for all my accounting these days. It’s wonderful and I highly recommend it. But I still use my own system to generate invoices.

Culling My Modules

About a year ago, I dabbled briefly with Travis CI. I even gave a talk about my experiences. The plan was that I would start to use it for all of my code. But real life intervened and I never got round to getting any further with that project.

This weekend, I finally made some progress. I added a .travis.yml file to all of my Github repositories that hold CPAN modules. I even fed the details through to Coveralls so I get test coverage reports. From there it was a simple step to building a dashboard that monitors the health of all of my CPAN modules.

And it’s not a pretty picture. You’ll see a lot of grey boxes on that page, indicating that Travis couldn’t run the tests or, worse, red boxes showing that the tests failed for some reason.

Yesterday I made a few quick fixes to some of the modules (particularly in the WWW::Shorten namespace) and a couple more of them now work. But I want to work out how much effort it’s worth investing in the ones that are still failing. And, widening my scope a little, I’ve decided to take a close look at my CPAN modules and work out which ones are worth keeping and which ones I should just delete.

For example, twelve years ago I was really excited about the idea of AudioFile::Info. Most people were ripping music to MP3s, but I wasn’t following the crowd and was using Ogg Vorbis instead. AudioFile::Info and its friends was an attempt to make it easy to extract information from audio files no matter which format they were it. I suppose it was a kind of DBI for ID3 tags. But twelve years on, does anyone really care about that any more? I switched all of my music collection to MP3 years ago. If I recall correctly, the AudioFile::Info modules use a convoluted hand-crafted plugin system which never worked as well as it should. I could probably switch them to use some kind of plugin architecture from CPAN. But is it worth the effort?

Then there is Guardian::OpenPlatform::API – a Perl wrapper around the Guardian’s API. I believe they changed the API end-point several years ago so the module doesn’t even work. But the fact that I’ve had no complaints about that, probably indicates that no-one has ever used it.

It’s a similar story for Net::Backpack. To be honest, I have no idea whether or not it still works. Is Backpack still running? Ok, I’ve just checked and they’re no longer offering it to new customers. But if I’m not a paying customer is there any way I can test that it still works?

Finally, there is the WWW::Shorten family of modules. I released a module called WWW::MakeAShorterLink back in 2002, but it was Iain Truskett who realised that there should be a family of modules around the (at the time new) URL-shortening industry. I took over the module when Iain passed away and I’ve been maintaining it ever since. But it’s a real pain to maintain. The URL-shortening industry changes really quickly. For a long time, new services were popping up all of the time (and many of them closed down just as quickly). I haven’t been anywhere near quick enough at releasing versions that keep up with all the changes. I suspect that at least a couple of the current test failures are down to services that have closed down. I should probably investigate those over the next few days.

I don’t think WWW::Shorten is in any danger of going away (but I need to find a better way to keep abreast of changes in the industry) but the other modules I’ve mentioned here (AudioFile::Info::*, Guardian::OpenPlatform::API and Net::Backpack) are on borrowed time. If you’re using them and you’d like to see new versions of them in the future then let me know. If you’d like to take over maintenance, then that would be even better.

If I don’t hear from anyone (and I strongly suspect that I won’t) then I’ll be removing them from CPAN in a couple of months time.

Mailing Lists

Over the years I’ve set up a few mailing lists for the discussion of various projects I’ve been involved with. There’s always an expectation that mailing lists will flourish without much input from me. But it never works out like that.

The truth is that most mailing lists just quietly die. And, in many cases, they end up attracting a lot of spam – which the owner of the list has to check on a semi-regular basis on the off-chance that there’s something interesting or useful in amongst the crap. There never is.

So I’ve decided to close a few mailing lists that didn’t seem to be going anywhere. I don’t suppose anyone will miss them, but I’ve taken a copy of the archives and I may do something with them at some point in the future.

The lists that I have removed are:

  • perlanet@perlhacks.com
  • perl-api-squad@perlhacks.com
  • perl-mooc@perlhacks.com
  • training-news@learnperl.co.uk
  • xml-feed@perlhacks.com

A couple of these lists have received slightly special treatment. The xml-feed list is advertised as the support email address for XML::Feed. I’ve redirected that address so that mail now comes to me. Hopefully my spam filters will ensure that I’m not overrun with spam from it before I work out a more permanent solution.

The other list that has been treated differently is the training-news one. That was set up so that people could get information about upcoming training courses that I would be running. I still think that’s useful, so I’ve replaced it with a new list (run by MailChimp). If you’re interested in keeping in touch with what I’m doing then please sign up to the new list by entering your email address below. (The same form will now appear in the sidebar on every page of this site.)


Sign up here for occasional email about stuff I'm doing with Perl, information about upcoming talks and training courses and other updates.

(I promise not to spam you.)


So, there you are. I’ve removed a few moribund mailing lists. I hope that hasn’t ruined anyone’s day.

Building TwittElection

I was asked to write a guest post for the Built In Perl blog. I wrote something about how I built my site, TwittElection, for the recent UK general election.

In the UK we have just had a general election. Over the last few weeks many web sites have sprung up to share information about the campaign and to help people decide how to vote. I have set up my own site called TwittElection and in this article I’d like to explain a little about how it works.

But why not go over to Built In Perl and read the whole thing there.

Incidentally, on 13th June, I’ll be giving a talk about TwittElection at this year’s OpenTech conference. If you’re interested in the positive impact that technology can have on society then you’ll, no doubt, find OpenTech very interesting.