On Feb 28, 2013 I gave a talk to Chicago.pm about Mojolicious. I called it an introduction, but I really wanted to show some of the features that sets Mojolicious apart. Because of this, the talk moves very fast. It hits routing and responses quickly, hits testing often, on all the way to well-tested non-blocking websocket examples.

I promised to get my slides up afterwards but life (i.e. my doctoral thesis) got in the way. Now with the release of Mojolicious 4.0 I thought I would take the opportunity to right a wrong and get the slides up; so here they are: http://mojolicious-introduction.herokuapp.com/!

The talk is itself a Mojolicious app, the source of which is available from on GitHub. Not only are all the code snippets shown in the talk included, not only do they all run, but they are actually what is rendered by the talk (DRY++), so what you see is what you get! Please leave any feedback and ask any questions. I may not see the responses here, so feel free to ping me elsewhere if needed.

People may have noticed my absence from the Perl world lately. I have been writing my Ph.D. thesis (179 pages on Ultrafast Electron Microscopy with my Physics::UEMColumn Perl module featured) and defense.

Ack is a tool for searching code and text. It works much like the unix tool grep, although it is imbued with the power of Perl. To mark the release of Ack 2.0 though I wanted to mention a few one-liners that made my life easier in this stressful time.

My thesis is written in many LaTeX files and one can probably imagine that searching those files was needed regularly. The biggest is for finding non-ascii characters. As I add content from old publications or external programs, lots of non-ascii characters can often come along for the ride. LaTeX is a very old program, well pre-dating unicode, and it has a very different way of adding special characters with its own markup. In fact parts of the compiling toolchain croak with unicode characters. So I found myself using

ack '[^[:ascii:]]'

regularly. Also I had to keep a list of all the abbreviations that I had used in the paper, but of course you forget if you have them all. I used this little bash-ack conglomeration to find all sequences of two or more upper-case characters, which is how I write my abbreviations,

ack -ho '\p{Upper}{2,}' | sort | uniq

I’m sure I used many other little ackings here and there, but these were the two I could remember off-hand. Thanks to Andy and everyone who has contributed to ack!

Now go use it to make your life easier!

Visit the new site: beyondgrep.com

Building on my (second) example from my recent post A Simple Mojolicious/DBI Example, I thought I would take it just a little bit futher. One of my favorite features of Mojolicious is that it comes with WebSockets out of the box! In this example I show how you can take the example script and allow it to run without refreshing the window.

A friend of mine is learning database administration, but for the first time needs to connect it to a webapp. Having done most of his work in MS Access, he has no idea what a web framework is, nor how one would connect a database to it. To help him learn I wrote up a little application using Mojolicious and SQLite.

Edit: MojoCMS has been renamed to Galileo and released to CPAN. Enjoy!

Over the holiday break, I decided to have a little fun learning some things about the web. I usually get my Perl fix through science, but several upcoming projects might have some web involvement; so I thought I should brush up. The following are some reflections on that experience.

The task I set myself was to make a micro CMS (it is currently named MojoCMS, but I’m not sure I like that), leaving most of the heavy lifting to freely available Javascript libraries. I didn’t think I would be especially good at writing the actual interface, but rather the routing and functionality would be my task. In a strange way, the result was a kind of nostalgic Perl experience; Perl was the glue in my project again, not the main/only language involved.

I used several great libraries, jQuery of course, jQuery-UI for a small part, HumaneJS for notifications (works great for websocket responses!) and PageDown for a real-time markdown renderer. FYI, PageDown is the editor from the StackOverflow team. These projects make life much easier, I can’t imagine writing that kind of Javascript by hand!

I must say, Javascript still eludes me. I can parrot it, but I’m sure I’m not doing it correctly. I think the problem lies with its dependence on the HTML/browser that is running it; the odd way that the language doesn’t have a use command, and that “page”-globals can be used, still feels odd. I can definitely see the need for jQuery, but that adds even further cognitive dissonance. Anyway, I think most of this is my shortcoming, not its.

HTML5/CSS3 on the other hand is brilliant. Its easy to make the markup do what you mean without too many machinations. Of course I pull in some libraries for that too, namely Bootstrap.

Back to the Perl of it though, I must say I have high marks for Mojolicious, for many reasons, but the highest are for Websockets! Now I know Mojolicious didn’t invent them, but it makes them easy. Using Websockets I was able to make the “save page” and “update main nav” windows save without reloading. That was rather cute and feels modern.

The biggest point I want to make (long ramblings aside) is my most recent addition: DBIx::Class. I’m a scientist, not a database admin. I have setup some PHP CMSes and have used mysql just enough to get them started; terrified the entire time. So much so that I started my CMS project with the idea of using DBM::Deep for as long as possible. Soon enough though, I was nesting hash-keys three deep and wishing I had objects; if I hadn’t needed persistence I would have reached for Moose long before.

I investigated KiokuDB, and while I had some hope for it, I think I would need someone sitting in on the setup process with me. Then I remembered, throughout YAPC::NA along with the list of my favorite Modern Perl modules, everyone else adds DBIx::Class. Ok they can’t all be wrong. They weren’t. Sure the syntax is a little different from Moose, but its not that hard. The payoff for me started even before running the site, in the deploy command. With a simple script I can create all the necessary tables and inject sample content without ever needing to write SQL! After this the ORM quickly and easily replaced the DBM::Deep vestiges throughout the code, and just like that I have readable, OO structures for users, pages and the menu configuration.

Anyway, if anyone wants to play with MojoCMS (or suggest a better name!) feel free. It is still very rough but I may try to see it forward a little further. Passwords are stored in the clear for now, so be careful! But this is my next task. After that and some other work on users (like being able add them through the website!) the thing might even be able to host a small site. Not bad for a one-week side project!

After (IMO) elegantly solving an SO question using my Tie::Array::CSV, I thought I might share it here to give you all an idea of when you might want to use it. This example is only reading the file, but remember that T::A::CSV gives you full row/column read/write access to the underlying CSV file in place.

The OP needed to find the column with a certain identifier which was 7 chars starting with a letter (in the example data below, this is the fouth column (i.e. index 3)). Then extract the number of repetitions of that identified in that column. Here was the solution that I posted.

#!/usr/bin/env perl

use strict;
use warnings;

use File::Temp;
use Tie::Array::CSV;
use List::MoreUtils qw/first_index/;
use Data::Dumper;

# this builds a temporary file from DATA
# normally you would just make $file the filename
my $file = File::Temp->new;
print $file <DATA>;
#########

tie my @csv, 'Tie::Array::CSV', $file;

#find column from data in first row
my $colnum = first_index { /^\w.{6}$/ } @{$csv[0]};
print "Using column: $colnum\n";

#extract that column
my @column = map { $csv[$_][$colnum] } (0..$#csv);

#build a hash of repetitions
my %reps;
$reps{$_}++ for @column;

print Dumper \%reps;

__DATA__
"ABCDEFGHIJK05","site","date1","ab96abc","date2"
"ABCDEFGHIJK05","site","date2","ab96abc","date2"
"ABCDEFGHIJK05","site","date1","cd98abc","date2"

(The OP gave one line of data, so I puffed it to 3, also to play blogs.perl.org’s width restrictions the data given here is rewritten. See the original post for the full stuff if you must.)

Of course I know you can do this with Text::CSV directly, but I like that it lets me think in terms of columns rather than objects and parsers and accessors.