Dave's Free Press: Journal: Module pre-requisites analyser

As a service to module authors, here is a tool to show a module's pre-requisites and the test results from the CPAN testers. So before you rely on something working as a pre-requisite for your code, have a look to see how reliable it and its dependencies are.

Dave's Free Press: Journal: YAPC::Europe 2007 report: day 2

A day of not many talks, but lots of cool stuff. Damian was his usual crazy self, and MJD's talk on building parsers was really good. Although I probably won't use those techniques at work as functional programming seems to scare people.

The conference dinner at a Heuriger on the outskirts of Vienna was great. The orga-punks had hired a small fleet of buses to get us there and back, and one of the sponsors laid on a great buffet. The local wine was pretty damned fine too, and then the evening de-generated into Schnapps, with toasts to Her Majesty, to her splendid navy, and to The Village People.

It wasn't all debauchery in the evening though - on the bus, I had a very useful chat with Philippe about Net::Proxy, and re-designing it to make it easier to create new connectors for it.

Dave's Free Press: Journal: CPANdeps

<a href=http://cpandeps.cantrell.org.uk/>CPANdeps</a> now lets you filter test results by perl version number, and also knows what modules were in core in which versions of perl. Hurrah!

Dave's Free Press: Journal: Thanks, Yahoo!

[originally posted on Apr 3 2008]

I'd like to express my warm thanks to the lovely people at Yahoo and in particular to their bot-herders. Until quite recently, their web-crawling bots had most irritatingly obeyed robot exclusion rules in the robots.txt file that I have on CPANdeps. But in the last couple of weeks they've got rid of that niggling little exclusion so now they're indexing all of the CPAN's dependencies through my site! And for the benefit of their important customers, they're doing it nice and quickly - a request every few seconds instead of the pedestrian once every few minutes that gentler bots use.

Unfortunately, because generating a dependency tree takes more time than they were allowing between requests, they were filling up my process table, and all my memory, and eating all the CPU, and the only way to get back into the machine was by power-cycling it. So it is with the deepest of regrets that I have had to exclude them.


[update] For fuck's sake, they're doing it again from a different netblock!

Dave's Free Press: Journal: YAPC::Europe 2007 travel plans

I'm going to Vienna by train for YAPC::Europe. If you want to join me you'll need to book in advance, and probably quite some way in advance as some of these trains apparently get fully booked.

Waterloo1740Fri 24 Aug
Paris Nord2117
Paris Est2245
Munich08590928Sat 25 Aug

The first two legs of that are second class, cos first wasn't available on Eurostar (being a Friday evening it's one of the commuter Eurostars and gets booked up months and months in advance) and was way too spendy on the sleeper to Munich. Upgrading to first class from Munich to Vienna is cheap, so I have.

Coming back it's first class all the way cos upgrading was nearly free ...

Vienna0930Fri 31 Aug
Zurich1402Sun 2 Sep
Paris Est1834
Paris Nord2013

Don't even think about trying to book online or over the phone, or at the Eurostar ticket office at Waterloo. Your best bet is to go to the Rail Europe shop on Picadilly, opposite the Royal Academy and next to Fortnums.

Dave's Free Press: Journal: Perl isn't dieing

Perl isn't dieing, but it tells me that it wishes it was. Last night it went out on the piss with Python and Ruby (PHP was the designated driver) and it did rather too many cocktails. It isn't quite sure what happened, but it woke up in the gutter in a puddle of its own fluids and its head hurts a lot.

It asked me to ask you all to keep the volume down.

Dave's Free Press: Journal: Wikipedia handheld proxy

I got irritated at how hard it was to use Wikipedia on my Treo. There's so much rubbish splattered around their pages that it Just Doesn't Work on such a small screen. Given that no alternatives seemed to be available - at least, Google couldn't find any - I decided to write my own Wikipedia handheld proxy.

It strips away all the useless rubbish that normally surrounds Wikipedia pages, as well as things like the editing functions which are also hard to use on portable devices. Internally, it's implemented using perl, LWP, and mod_perl, and is hosted by Keyweb.de.

Dave's Free Press: Journal: YAPC::Europe 2007 report: day 3

My Lightning Talk on cpandeps went down really well, although as José pointed out, I need to fix it to take account of File::Copy being broken. I also need to talk to Domm after the conference is over to see if I can get dependency information from CPANTS as well as from META.yml files.

There were lots of other good lightning talks. Dmitri Karasik's regexes for doing OCR, Juerd Waalboer's Unicode::Semantics, and Renée Bäcker's Win32::GuiTest were especially noteworthy.

Richard Foley's brief intro to the perl debugger was also useful. Unfortunately Hakim Cassimally's talk was about debugging web applications, which I'd not noticed on the schedule, so I didn't stay for that.

And finally, Mark Fowler's grumble about why perl sucks (and what to do about it) had a few interesting little things in it. I am having vaguely sick ideas about mixing some of that up with an MJD-stylee parser.

At the auction I paid €250 to have the Danish organisers of next year's YAPC::Europe wear the Swedish flag on their foreheads. This, I should point out, was Greg's idea. I would never be so evil on my own.

Dave's Free Press: Journal: POD includes

One of my CPAN distributions is CPAN-FindDependencies. It contains a module CPAN::FindDependencies, and a simple script that wraps around it so you can view dependencies easily from the command line. That script, naturally, has a man page. However, that manpage basically says "if you want to know what arguments this program takes, see the CPAN::FindDependencies docs". This is Bad from a usability point of view, good from a not-duplicating-stuff point of view, and good from a laziness point of view. Which means that it's Bad.

So, the solution.


#include shared/parameters


and some Magic that does the cpp-stylee substitution at make dist time. Note the 'dist' section in my call to WriteMakefile.

This is, of course, crying out to be made less horribly hacky, but it works for now, so I'm happy.

My original idea was to write some crazy shit that would do the #include at install-time, when the user was installing my code. But that has the disadvantage that tools like search.cpan wouldn't show it properly, as they simply look at the files in the distribution. So this does the #includes at the last moment just before I package up the code and upload to the PAUSE. You lovely people get the right documentation in all the right places, I only have to maintain it in one place so it stays in sync, and (in the interests of Laziness) I don't have to remember to run any extra scripts before releasing, make dist just Does The Right Thing.

Dave's Free Press: Journal: Bryar security hole

Someone on IRC reported a bug in Bryar. Namely that a Naughty Person can exploit the feature that notifies you of blog-spam by email to execute arbitrary code on your machine, as the user you run Bryar under.

A patched release is on the way to the CPAN, and you are strongly urged to upgrade.

Dave's Free Press: Journal: cgit syntax highlighting

NB: since writing this I have migrated all my code to Github and stopped using cgit. Therefore many of the links no longer work

For the last few months I've been using git for my version control system. It's better than CVS because it can handle offline commits. So if I'm using my laptop on a train, I can still use version control without having to have a notwork connection.

And to give a pretty web front-end to it for other people to read code without having to check it out of the repository, I use cgit, which I mostly chose because it's a dead simple CGI and not a huge fancy application.

One problem with cgit is that by default it doesn't do code highlighting. But it has the ability to run blobs of code through any filter you care to name before displaying them, so to get something nice like this all you need to do is write a highlighter and add a single line to your cgitrc:


My highlighter program is this:

   1 #!/usr/local/bin/perl
3 use warnings;
4 use strict;
6 my $file = shift;
8 if($file =~ /\.(p[ml]|t)$/i) {
9 system "/usr/local/bin/perltidy -html -st -ntoc -npod -pre -nss -nnn"
10 } else {
11 system "cat -n";
12 }

Dave's Free Press: Journal: Devel::CheckLib can now check libraries' contents

Devel::CheckLib has grown a new feature. As well as checking that libraries and headers exist, it can now also check that particular functions exist in a library and check their return values. This will be particularly useful if you need to check that a particular version of a library is available.

It works if you have a Unixish toolchain. I need to wait for the CPAN-testers reports to see if I managed not to break anything on Windows. Unfortunately, even though the lovely Mr. Alias has worked hard to make Windows machines available to developers, I found it to be just too hard to use. Even downloading my code to the Windows machine was hard, as Windows seemed to think it knew better and shouldn't download the file I told it to download. Then once I had downloaded it, Windows decided to hide it somewhere that I couldn't get to using the command line. So I gave up.

I might try again once there are some decent tools on the machines: wget, tar, and gzip at minimum, as given those I can quickly bootstrap anything else. Software development isn't just about having compilers available.

Dave's Free Press: Journal: I Love Github

Github makes accepting patches from other people and applying them soooooo easy!

Instead of having to extract the patch from an email onto my workstation and manually apply it, applying this contribution was a simple matter of clicking on one button.

Thanks Mark - and thanks Github as well!

And I was also amused to see that the new release of Net::Random was exactly five years after the previous one. This adds support for fetching your randomness over SSL.

Dave's Free Press: Journal: CPAN Testers' CPAN author FAQ

Barbie recently posted that David Golden recently posted regarding a comment from Leon Timmermans on IRC. Leon highlighted a problem when CPAN authors try to find information about CPAN Testers, and how they can request testers to do (or not do) something with a distribution they've just uploaded.

The page they are looking for is the CPAN Author FAQ on the CPAN Testers Wiki. Although there is plenty of information for authors, the page doesn't appear prominently on search engines when some searches for that kind of information.

As such, David has suggested that people tweet or post about the page, which includes this post :-)

Dave's Free Press: Journal: Thankyou, Anonymous Benefactor!

I got home this evening to find an Unexpected Parcel waiting for me, full of books. I have no idea who it's from, but I'm guessing that it's from someone who finds <a href=http://deps.cpantesters.org/>CPANdeps</a> useful. Thank you, Anonymous Benefactor! Your generosity is much appreciated!

Dave's Free Press: Journal: Number::Phone release

There's a new release, <a href=http://www.cantrell.org.uk/david/tech/perl-modules/Number-Phone-1.58.tar.gz>version 1.58</a>, of Number::Phone, my set of perl modules for picking information out of phone numbers. Changes from the previous release are that Mayotte, Reunion and Comoros can't decide which country is which, and there's the usual updates to the database of UK numbers, mostly to support the <a href=http://www.ofcom.org.uk/media/news/2007/02/nr_20070213b>new 03 numbers</a>.

Dave's Free Press: Journal: Palm Treo call db module

To make up for a disappointing gap in Palm's software for the Treo smartphone, I wrote a <a href=http://www.cantrell.org.uk/david/tech/treo/call-dumper/>small perl script</a> to parse the database that stores my call history. I then re-wrote it as <a href=http://search.cpan.org/search?query=Palm%3A%3ATreoPhoneCallDB>a re-useable module</a> which also figgers out whether the call was incoming or outgoing.

Dave's Free Press: Journal: Ill

I am ill. I've been ill since Thursday, with a cold. You're meant to be able to cure a cold with [insert old wives tale remedy here] in 5 days, or if you don't, it'll clear itself up in just under a week. So hopefully today is the last day.

So what have I done while ill?

On Friday I became old (see previous post), and went to the Byzantium exhibition at the Royal Academy. It was good. You should go.

Saturday was the London Perl Workshop. My talk on closures went down well, and people seemed to understand what I was talking about. Hurrah! I decided that rather than hang around nattering and going to a few talks, I'd rather hide under my duvet for the rest of the day.

I mostly hid on Sunday too, and spent most of the day asleep. In a brief moment of productivity, I got my laptop and my phone to talk to each other using magic interwebnet bluetooth stuff. I'd tried previously without success, but that was with the previous release of OS X. With version X.5 it seems to Just Work, so no Evil Hacks were necessary.

The cold means that I can't taste a damned thing, not even bacon. So now I know what it's like to be Jewish. Being Jewish sucks.

And today, I am still coughing up occasional lumps of lung and making odd bubbling noises in my chest, although my nasal demons seem to be Snotting less than they were, so hopefully I'll be back to normal tomorrow.

Dave's Free Press: Journal: CPANdeps upgrade

While you won't notice any changes, there have been biiiig upgrades at CPANdeps. Here's the diff.

Until now, it's used a SQLite database of test results that I downloaded every day and then mangled a bit to do things like add some necessary indices, figure out which reports are from dev versions of perl, and so on. That worked really well back in the summer of 2007, when there were only half a million reports in the database. I started worrying a bit at the beginning of 2009 when we hit 3 million, but the update happened overnight so I didn't care. But now that we've got over 6 million reports, the update would take anywhere between 8 and 14 hours. Not only is that not sustainable given the current growth rate, it also hurts the other users on that machine, because almost all of that time is spent waiting for disk I/O - which means that they're also waiting for the disk. On top of that, when you have big databases, a SQLite CGI ain't a great idea because indices have to be fetched from disk every time, so reads pound the disk too. Doubleplusungood!

Fun fact: SQLite is great for prototyping, but it doesn't scale :-)

So now it uses MySQL. Having a database daemon running all the time means that there's now some caching, so reads are quicker. In addition, given that I can't just simply fiddle with the structure of the database that I download to produce what I want, and instead have to import the data into MySQL, it now only imports new records, so the daily update takes only a few seconds.

I also re-jigged the structure of how it caches test results. Instead of being all in one directory with hundreds of thousands of files, they're split into a hierarchy. This probably won't have any significant effect on normal operations, but it will certainly make it faster for me to navigate around and see what's going on when people submit bug reports!

Dave's Free Press: Journal: YAPC::Europe 2006 report: day 3

There were quite a few interesting talks in the morning, especially Ivor's one on packaging perl applications. Oh, and mine about rsnapshot, of course, in which people laughed at the right places and I judged the length of it just right, finishing with a couple of minutes left for questions.

At the traditional end-of-YAPC auction, I avoided spending my usual stupid amounts of money on stupid things, which was nice. Obviously the hundred quid I put in to buying the hair style of next year's organisers wasn't stupid. Oh no. Definitely not.

An orange mohican will suit Domm beautifully.

Dave's Free Press: Journal: Graphing tool

I made a shiny thing! It can plot arbitrary functions of the form x=f(y) or y=f(x). Under the skin, it just massages its arguments and passes them through to Gnuplot. Here's the source code.

Update: now 48.3% even shinier - see on the right

Dave's Free Press: Journal: Travelling in time: the CP2000AN

My mad experiment in CPAN mirrors has grown a couple of new tentacles. Previously it could be a perl-X.Y.Z-specific mirror, such as the CP5.6.2AN, or an OS-specific mirror such as the cpMSWin32an. Now it can combine the two such as in the CP5.8.8-irixAN and all of those can optionally be combined with a date/time to only include stuff that was already on the CPAN as at that time, such as at the CP2000AN.

Why do this? Let's assume that you have a large complex application which uses lots of stuff from the CPAN, and depends on Elk version 1.009 and ListOfDogs version 5.1, and will break with any later version of Elk (or of ListOfDogs). You get a feature request from a user, and think "ah-ha, there's a module for that", and so you go to install Some::Module. Unfortunately, the latest version of Some::Module depends on Some::Other::Module which in turn needs Another::Module which needs Elk 1.234, so your CPAN client merrily upgrades Elk, breaking everything. Doom and Disaster. Having a CPAN "mirror" nailed to the date of the last release of Elk and ListOfDogs that works for you will save you from pain, suffering, and the Dark Side. Either you'll get older versions that Just Work, or you'll get nothing, and nothing is far better than breaking everything!

Dave's Free Press: Journal: XML::Tiny released

I have released my XML::Tiny module. The parser at its core is less than twenty lines of code. Pretty easy to follow code too, I think, and that also includes error handling. One of my aims in writing it was to keep memory usage and code to the absolute minimum, so it doesn't handle all of XML. The documentation says that it supports "a useful subset of XML". Personally, I think it supports the useful subset. It's certainly enough to parse the data I get back from Amazon when I use their web services, and to parse an RSS feed.

Dave's Free Press: Journal: YAPC::Europe 2007 report: day 1

As is becoming normal, I used the times between talks to bugfix some of my modules - this time Tie::STDOUT and Data::Transactional. The former was failing on perl 5.6, the latter on 5.9.5. The former was a bug in perl (you can't localise tied filehandles and expect the tieing to go away in 5.6, so it now declares a dependency on 5.8), the latter was a bug in my code.

Philippe Bruhat's talk on Net::Proxy was great - you can tell it's great because I came away with ideas for at least four things that I need to write. First up will be a plugin for it to allow the user to specify minimum and maximum permitted data rates for proxied connections. This will permit bandwidth limits for maximum permitted rates, but will also help to defeat IDSes doing traffic analysis if you specify a minimum permitted data rate.

This will protect (eg) ssh sessions from being identified based on their very bursty traffic pattern, by "filling in the blanks" with junk data.

In the evening, the CPAN-testers BOF was productive.

Header image by Tambako the Jaguar. Some rights reserved.