Dave's Articles and Stuff

perl hacks: Crufty Old Perl

2010-03-11T18:05:36Z

It's eighteen months since I wrote "Why Corporates Hate Perl" and it's worth pointing out that the company I discussed in that article which was dropping Perl in favour of PHP and Java is still employing as many good Perl programmers as it can find.

I talked in that article about some rather unsubtle social engineering that had been going on at that company. Management had started to talk about Perl as a "legacy language" in an attempt to persuade the business that they really don't want their applications written in Perl. That doesn't seem to have been as successful as I feared it would be.

But there's another kind of social engineering that I've seen going on. And this is happening at the developer level. I've lost count of the number of times I've been sitting in meetings with developers, discussing ways to improve the quality of crufty old Perl code when someone throws in the (more than half-serious) suggestion that we should just rewrite the whole thing using Rails or Django.

There seems to be this idea that switching to a new framework in a new language will act as some time of magic bullet and that suddenly all of our problems will be solved. There are so many ways that this perception is flawed, Here are my two favourites.

The current system is old and crufty not because it's written in Perl, but because it was written by people who didn't understand the business requirements fully, didn't know their tools particularly well or were under pressure to deliver on a timescale that didn't give them time to design the system properly. Often it's a combination of all three. Given the time to rewrite the system from scratch, of course it will be better. But it will be better because the business is better understood and tools and techniques have been improved - not because it's no longer written in Perl.
Frameworks in other languages are not easier to use or more powerful than frameworks in Perl. Anything that you can do with Rails or Django you can do just as easily with Catalyst. It's using a framework that's the big win here, not the particular framework that you use. Sure, if you're a Ruby house then using a Ruby framework will probably match your existing developers' skills more closely but if your current system is written in Perl then, hopefully, you have a team of people with Perl skills and that's going to be the language you'll want to look at.

I'm tired of Perl being seen as a second-class citizen in the dynamic languages world. I freely admit that there's a lot of bad Perl code out there (I'll even admit to writing some of it) but it's not bad Perl code because it's Perl, it's bad Perl code because it's bad code.

This is what the Perl marketing initiative. We need people to know that Perl is not the same language that they stopped using ten years ago. Modern Perl can compete with any of the features of any other dynamic language.

By al means, try to get the time to rewrite your crufty old systems. But rewrite them in Modern Perl. You'll enjoy it and you'll be really productive.

davblog: Gigs for Old Gits

2010-03-07T11:06:49Z

It's been a busy couple of weeks for gigs. On the assumption that at least some of my readers have similar tastes to me, here are brief reviews of the three gigs I've seen in the last couple of weeks.

Fairport Convention, Union Chapel, 20th Feb
This is the second year running that I've seen Fairport Convention on their "Wintour" at the Union Chapel. Last year was the first time I had seen them (which is bizarre for a band I've been a fan of for over thirty years). I can't quite put my finger on it, but this year's show wasn't as enjoyable as last year's. I suspect it was down to the number of songs taken from later Fairport albums that I'm not at all familiar with. Oh, and the arrangement of Matty Groves was very strange. The long instrumental that ends the song was unrecognisable.

Thomas Dolby and Friends, Union Chapel, 28th Feb
Something a little more up to date. This was Thomas Dolby bringing back together the band who had recorded and toured his second album, The Flat Earth. As an extra twist, the band (who haven't played together for over twenty-five years) didn't rehearse at all. They met on stage and worked the songs out in a two-hour "live rehearsal". They then went of for a brief break before returning to play a half-hour set.

The rehearsal was fun. And the band sounded great for a band eho hadn't played together for so long. There were also a few guest stars - including Trevor Horn who played bass on "Airwaves". The only slight disappointment was that the rehearsal overran so the final set had to be cut short.

John Cale, Royal Festival Hall, 5th March
I'm not a huge John Cale fan. I generally like the stuff of his that I hear, but I haven't really heard much of it. This concert had him playing the whole of hist album "Paris 1919" (from 1973). This isn't an album that I'd heard at all until I started to listen to it in preparation for this show and it's really not that representative of the rest of his music. But it's a great album and it was interesting to hear it all played live. It is, however, a rather short album (many were back in the early 70s) and that part of the show only lasted forty minutes. After a short break (and it was really short) the band returned to play another forty minutes of "the best of John Cale". I was pretty surprised to realise that I recognised most of these songs. All in all, a great night out.

perl hacks: Plug Plug Plug

2010-03-01T21:50:34Z

I've got another set of public training courses coming up next month. They will be held at the Imperial Hotel in Russell Square, London.

There are three one-day courses - Introduction to Perl, Intermediate Perl and Advance Perl. They're running on the 13th, 14th and 15th of April.

More details on my training web site. Hope to see some of you there.

p.s. Gabor has been kind enough to advertise the courses on his newly revamped CPAN Forum site - so the least I can do is to repay the favour and recommend that you have a look at the site.

davblog: OLB Non Enrolled Non Endorsed 1

2010-03-01T15:20:37Z

When communicating with your customers, it's important to look at the information that you're sending from their point of view. Are they really going to be interested in the information that you send?

Earlier today I finally got round to unsubscribing from the MBNA marketing emails that have been annoying me for months. To confirm my unsubscription they sent me an email which started with this:

We are sorry that you unsubscribed from the newsletter OLB Non Enrolled Non Endorsed 1

Is there really any customer who is going to be even slightly interested in that level of detail? I don't care what your internal name for the newsletter is. I just want to stop seeing it in my inbox.

davblog: The Learning Guitar

2010-03-01T09:35:33Z

I don't play the guitar very well at all. I'll sometimes say that I play it better than average, but that's a claim that can only be justified by pointing out that the vast majority of people don't play guitar at all so anyone who knows two or three chords is already well above average.

I have, however, been playing guitar (for some loose definition of the word "playing") for a rather long time. Just how long was brought home to me this weekend.

We're having a lot of building work done in our house over the next few months and as a precursor to that we have had to clear pretty much everything out of the first floor. A lot of stuff has gone into storage, but we also took a lot of stuff to our local tip on Saturday. That load included three guitars and one of them was "The Learning Guitar".

The Learning Guitar was (as its name suggests) the guitar that I first learnt to play on. It was a cheap nylon-stringed Spanish guitar that my parents bought me when I started to take lessons. That was very soon after I started at secondary school in September 1974. There was an after school class which I joined. I think I stopped going after only a couple of months as we were learning boring stuff like "When The Saints Go Marching In" when I wanted to be playing stuff by Slade or David Bowie. At the time I assumed that we weren't learning that stuff because it was too difficult for beginners. Later I realised that a lot of the music I enjoyed was actually just as simple as the stuff we were taught - it was just that the teachers were a bit old-fashioned.

I carried on teaching myself though. I bought a Mel Bay book and spent hours practicising in my bedroom. Of course I had no real idea what I was doing and I picked up a number of bad habits that hamper my playing even now. But I was enjoying myself.

Soon after moving to London to go to university I got another guitar. It was a Fender F3. A much nicer-sounding guitar. My original guitar was somewhat ignored. For a year I shared a flat with someone who played guitar really well and by watching him my playing improved a lot.

But the Learning Guitar still had some life in it. Over the next fifteen or twenty years I took to lending it to friends who wanted to learn guitar. The story was always the same. Someone borrowed it for a couple of years and when they thought the time was right, they'd buy a better guitar and give the Learning Guitar back to me. It was during this period that the guitar acquired its nickname. The last person to borrow it like this was my step-daughter who took it with her when she went to university. As always, i came back after a couple of years.

Over the last ten years, I've played guitar a lot less. I couldn't really justify storing the four guitars that I had cluttering up my study. So this weekend they all went except the Fender. We loaded up a van and took them to the Wandsworth Council dump. Of all of the things that I threw away on Saturday, the Learning Guitar was the thing that I felt most guilty about. I threw it high up on a mountain of rubbish at the dump. At one point I considered trying to retrieve it, but it was too far away.

It was never a particularly good guitar. But a lot of people have strummed their first tentative chords on that guitar. It's a shame to see it go.

Later this week, I hope to get rid of my collection of records. That has sat in a cupboard unused for over ten years. There's really no reason to keep it. But if you think I have got needlessly sentimental about an old guitar, you haven't seen anything yet. I'll be getting far more nostalgic about the records.

davblog: Homeopathy Petition

2010-02-25T08:52:11Z

We're all, of course, very happy about the results of the House of Commons Science and Technology committee's evidence check on homeopathy. But it's important to realise exactly what has happened. This is a House of Commons committee which has produced a list of recommendations. The government is under no obligation at all to take any notice of those recommendations. Unfortunately, Richard Wiseman's tweet, "yipppeeee it's official, NHS will no longer give people smarties", is likely to be somewhat premature.

So that's why I've set up a petition on the number 10 web site. The petition says:

We the undersigned petition the Prime Minister to Implement the recommendations of the House Commons Science and Technology committee evidence check on Homeopathy.

The House Commons Science and Technology committee has recently undertaken an evidence check on the usefulness of homeopathy and has now published its report.

The conclusions are unequivocal. They say "To maintain patient trust, choice and safety, the Government should not endorse the use of placebo treatments, including homeopathy. Homeopathy should not be funded on the NHS and the MHRA should stop licensing homeopathic products."

The government should implement these recommendations as soon as possible.

If we can get enough people to sign this petition I hope we can send a message to the government letting them know that we support the committee's findings and don't want the NHS's money wasted on nonsense like homeopathy.

Of course, this close to an election, the government is likely to be very wary of making any kind of a statement that might lose them support amongst the woo-mongers. We need to persuade them that skeptical (and rational) voters outnumber the idiots. At the very least, we should be able to get more signatures than this ridiculous petition.

So please sign the petition. And please pass the details on to anyone else who might be interested. The battle has not been won yet.

davblog: NHS Money Wasted on Homeopathy

2010-02-22T12:55:39Z

Don't have time to go into the detail that it deserves, but the House of Commons science and technology committee has published the results of its evidence check on homeopathy. The results won't, of course, come as any surprise to anyone who has been following the debate. But I have to admit to be impressed by the lack of ambiguity in their conclusions. This is paragraph 157:

By providing homeopathy on the NHS and allowing MHRA licensing of products which subsequently appear on pharmacy shelves, the Government runs the risk of endorsing homeopathy as an efficacious system of medicine. To maintain patient trust, choice and safety, the Government should not endorse the use of placebo treatments, including homeopathy. Homeopathy should not be funded on the NHS and the MHRA should stop licensing homeopathic products.

Absolutely no equivocation there.

So what's the next step? When to the homeopathic "hospitals" get closed down? When does the NHS get that money back for real medicine?

Update: The Woo-mongers in the House of Commons don't plan to take this laying down. They've proposed an Early Day Motion criticising the committee's report. Of course, only MPs with no grasp of science will be signing it. If your MP is on this list, then I suggest a strongly worded email might be in order.

davblog: Homeopathic Dilutions

2010-02-22T16:25:44Z

Like many press outlets, the Daily Mail pre-empted the publication of the Science and Technology committee report and published a story yesterday summing up the MPs' findings. Of course the Daily Mail is the home of the gullible reader and a good number of the comments on that story are attempting to defend the woo-mongers.

The Mail often stop taking comments on their stories after about a day (giving no indication that they've done so) and the number of comments on this story has stuck at eighteen since I first saw it last night so we must assume that they won't publish any more.

This is a shame as there's quite a lot of unchallenged nonsense there. In particular, the most recent comment published is from Dave in Basingstoke. Someone previously in the discussion had mentioned the ludicrous amount of dilution in homeopathic solutions. Dave replies with this:

"But scientists point to the fact that the 'cures' are so diluted that the cannot possibly contain even a single molecule of the original substance."

Ha! Maybe a climate change pseudo-scientist would say that, but a chemist never would because it isn't true. If you dilute a solution of anything by a million to one, there will still be thousands of molecules of the substance present in the diluted solution. The body can detect that amount, and work on it.

Let's ignore his childish dig at climate change and get to the meat of his argument. Dave thinks that is you dilute something by a factor of a million then there will still be molecules of the original substance in the solution. And he's right there. No one will argue with that fact at all. But homeopathic remedies aren't million to one dilutions.

Homepathic dilutions are given a number on the "C scale". Each time you dilute something by a factor of a hundred, you get another point on the C scale. A dilution of a hundred to one would be called 1C. Dilute that solution be another hundred to one (that's now ten thousand to one from the original solution) and you get to 2C. Another step to 3C gives us a dilution of a million to one from the original solution. That's about the level of dilution that Dave is talking about.

But homeopaths don't stop there. 3C dilutions are nothing. Remember a key tenet of homeopathy is that the weaker the dilution, the stronger the effect. Homeopaths carry on diluting their solutions again and again and again. Next time you're in Boots have a look at the numbers on the tubes of homeopathic remedies that they sell. You'll see that 30C is a really common dilution. That solution has been diluted by a factor of a hundred to one thirty times. The original solution has been diluted by a factor of one to a number which is one followed by sixty zeroes. That's a huge number. With numbers like that involved, it's perfectly reasonable to say that there is none of the original material left.

Here's an example to help you get to grips with those numbers. The number of water molecules in a swimming pool is going to be around a one followed by thirty two zeroes. One molecule of something else in that pool will be equivalent to a 16C homeopathic remedy. See the Wikipedia entry on homeopathic dilutions for more examples like this.

This is why the slogan for the 10:23 campaign is "There's nothing in it". It's literally true. There is no active ingredient left in any homeopathic remedy that you find.

I'd love it it if Dave from Basingstoke found this entry. It would be great if he could see just how misinformed he is.

perl hacks: Marketing Perl at FOSDEM

2010-02-19T13:04:15Z

It's two weeks since I went to FOSDEM and I promised to write an article about what happened there. Better do that before I forget everything.

Some time ago, Gabor applied for a Perl stand at this year's FOSDEM. The idea was that we could go along and promote Perl to people who are part of the Open Source community but not part of the Perl community.

When I first arrived at the venue, it took me some time to find the Perl stand. This was largely because I was searching in the wrong building. I forgot that FOSDEM is spread over several buildings at the ULB. I had assumed that we'd be in the main building, but we were actually in another building along with most of the stands.

The Perl Foundation had paid for some stuff for us to give away from the stand. We had some postcards listing Perl events in Europe this year and some round tuits. There were also a few other leaflets promoting particular Perl events.

I think it was unusual for a programming language to have a stand at the conference. Plenty of other projects had stands, but I didn't see any other languages. A lot of the other stands were promoting projects that they were able to demonstrate. I think it's hard to demonstrate a programming language in a situation like that.

We got a lot of people passing by the stand and many of them stopped to talk. The round tuits attracted the most attention, but it was sometimes hard to explain the joke to people whose first language wasn't English. There were at least a couple of times when I just gave up trying.

On Saturday afternoon, Juerd arrived. He brought a project with him and we set that up projecting a hastily assembled slideshow on the wall opposite us. That also drew a lot of attention to the stand. In the future I think it's a good idea to plan something like that in advance.

Just about everyone who we talked to knew about Perl. And most of them had used it at some point. Most of the people I spoke to were still using it to some extent. But very few of them knew about the "Modern Perl" projects that we were promoting (Catalyst, Moose, DBIx::Class, etc) or the huge number of Perl events that take place i Europe every year. I think we got some of them interesting in Modern Perl and I'm hoping that we'll see a few new faces at various Perl events this summer. I promised to buy a drink for some of them if they come along to YAPC::Europe. If they all take me up on it, it might get a bit expensive.

Our presence at the conference was all very experimental. We know that this is something that we want to do more of, but we're just working out the most effective approaches to take. But I think that we can count this attempt as a success and take the lessons learned forward to other non-Perl conferences. The next one on the list is CeBIT.

Other people have also written about this event: Gabor, Claudio, Erik, Salve.

davblog: David Wright and Twitter

2010-02-17T08:58:32Z

you can put lipstick on a scum-sucking pig but it is still a scum-sucking pig

That's apparently what Labour MP David Wright said about the Tory party on Twitter on Monday. I say "apparently" because he claims he didn't say it. He says that his tweets have been tinkered with. He says that the words "scum-sucking" have been inserted by someone else. But how likely does that seem? I think that we need to consider three alternatives.

The tweet was changed by someone before it was passed to Twitter. This would imply that Wright has someone else who actually runs his Twitter account for him and who decided to have a little fun. No such Twitter assistant has been mentioned by Wright, so I think we can dismiss this possibility.
The tweet has been edited since it was initially submitted to Twitter. Now Twitter doesn't offer users the facility to edit old tweets so this would involve someone hacking into the the Twitter database, tracking down one tweet by an obscure British politician and changing that. I know that if I wanted to start hacking into Twitter and changing tweets, David Wright would be a long way down my list of potential targets. I think we can dismiss this possibility too.
David Wright is being dishonest. Given that his first response to people complaining about the tweet was "Oh dear, upsetting Tories again. Must've hit a nerve" and that the tampering story only emerged later, I think this is a far more likely explanation.

Which leaves us wondering why he thought that lying about it like this was a good idea. This time I think we have two options to consider:

Wright knows nothing about how any of this stuff works and doesn't realise how ridiculous his story sounds.
Wright knows how ridiculous he sounds, but believes that none of his constituents understand this internet stuff so they won't realise that he's talking nonsense.

To be honest, I don't think that either of those alternatives show Wright in a particularly good light. In the first option, Wright is an elected representative who is apparently jumping on the Twitter bandwagon without understanding the first thing about the tools he is using. And in the second he's someone who doesn't mind deliberately lying to the electorate as long as he thinks there's a good chance that he won't be found out.

I have way of knowing which of those two alternatives is an accurate description of what happened here. But if I was voting in Telford I'd be having a serious think about whether I wanted a man like Wright representing me in Parliament.

Update: David Wright has issued a statement. He says:

My Twitter account has been hacked into and changed," he said. "I have demanded that Twitter provide me with the identity of whoever has inputted into my site. I will make a further statement when that information is available, and I will be seeking a meeting with ministers to discuss the general protection of blog sites.

To which I can only respond "Bwah Ha Ha!"