I've released a new version of MooseX::Role::Loggable: 0.110. It provides some improvements and basically a more steady version of it.

Here's a description of what it is, what the improvements are, and some of the considerations in doing them.

There's a very common Perl idiom for getting "top N elements" from an array: @top = (sort @a) [0 .. $n - 1]. Mostly, it's good enough for anything one would dare to store in RAM.

Then, there is Sort::Key::Top, which allows you to write @top = top $n => @a. Yet another syntax sugar?

Not even close! While the docs don't state it boldly, it is:

1. a XS based module
2. partition-based general selection algorithm (also known as quickselect) implementation

So, expect it to be fast. How fast?

Subroutines that take more than a single argument should really be using something like MooseX::Params::Validate.

Consider:

sub vivisect { 
    my ( $self, $args ) = @_;
    confess 'Expected a hashref of arguments' unless 'HASH' eq ref $args;

    my $hamster = $args->{hamster};

OK, so we know it accepts a hashref of arguments, and what's more, we know one of them is called hamster. But: what constitutes an acceptable hamster? What do we want to do if we don't have a hamster? What other arguments am I going to need? All of this is mental load at 7am and sure, maybe there's documentation, but maybe the intern snuck in some new options and didn't tell anyone...

Compare and contrast this to:

sub vivsect {
      my ( $self, %params ) = validated_hash( \@_,
          hamster => { isa => 'Hamster', default => sub { Hamster->animate(), } },
      );

Yes, it's some more typing. But now, as a reader, I know what's what. I know a hamster is optional, and I know what'll happen if I don't include it. I know no-one else has been adding other options like guinea_pig, because they'd show up there.

I just found something interesting.. well, at least, fun:

Package namespace         installed    latest  in CPAN file
Perl::MinimumVersion           1.29      1.30  CHORNY/Perl-MinimumVersion-1.30.tar.gz

After installing Perl::MinimumVersion, I get:

Package namespace         installed    latest  in CPAN file
Perl::MinimumVersion::Reason      1.20      1.29  CHORNY/Perl-MinimumVersion-1.29.tar.gz

And if I ask to install Perl::MinimumVersion::Reason, yeah, of course, I get:

Package namespace         installed    latest  in CPAN file
Perl::MinimumVersion           1.29      1.30  CHORNY/Perl-MinimumVersion-1.30.tar.gz

Probably a good idea to add a bug report... later.

But fun to have problems with versions on a module that deals with versions.

Welcome to Perl 5 Porters Weekly, a summary of the email traffic of the perl5-porters email list. Sorry I didn't publish a summary last week. Although there was list traffic I didn't find any messages I wanted to summarize.

This week's topics include:

• perl 5.17.6 is now available!
• On deprecating unescaped literal left brace
• Parrot 4.10.0 released
• Perl in Git on Windows?
• Move tests not using t/test.pl into a separate directory
• Hash randomisation breaks CPAN

I've just released the first version of prereq-grapher, a script which generates the dependency graph for a module or script in any of the formats supported by Graph::Easy. The functionality lives in App::PrereqGrapher, which in turn uses Perl::PrereqScanner to extract dependencies.

Scannerless parsing

[ This is cross-posted from the new home of the Ocean of Awareness blog. ]

I've been working on a "scannerless" Marpa interface. "Scannerless" means that the user does not need to write a separate lexer -- the lexer (scanner) is included in the parser. One of my working examples is the synopsis from the main Marpa::R2 POD page, rewritten to do its own lexing:

    
:start ::= Expression
Expression ::=
       Number
    || Expression '*' Expression action => do_multiply
    || Expression '+' Expression action => do_add
Number ~ digits '.' digits action => do_literal
Number ~ digits action => do_literal
digits ~ [\d]+
    
      

Here the notation is that of my last post, as documented here. New for the scannerless parser are

The great detective was staring at the door, as he had done for the past two weeks. He needed a case to occupy that mind. Thankfully today the door opened and Holmes had a case.

A man stepped in and introduced himself as Mr. Mokko.

”Watson, here is a man having troubles with Perl.”

”Holmes, how can you know that?”

”We can tell from the lines on his face, the stiff wrists and the pads of his fingers that he a much maligned sysadmin; from the Hawaiian shirt and the hat that he’s into the Perl scene. The scowl and the fact that he’s here on our doorstep tells me that he’s having troubles.”

Holmes looked back to the man and said, “Come now, you must tell me the tale.”

I’ve just released a new version of Method::Signatures: 20121201, a.k.a. yesterday.  This one has been a long time coming—I thought for a while there that $work was going to either bury me or sap my will to live—but it’s finally here, and I hope you MS fans out there will be rejoicing.  Let’s take a look at some of the goodies.

(By the way, most of these awesome new features came from the Damian, as I described in my post about Git and patches.  The remainder come from schwern, who is of course the original author of MS.  This time around, I really am just the guy who put it all together and uploaded it for all y’all.)

where Constraints

It was late afternoon of a chill November in Paris. I was walking along the quai, lost in a brown study. Looking up, I saw my friend C. Auguste Dupin approaching me.

"Ah, bon soir, mon ami," said Dupin, "and what brings you beside the Seine on this crisp evening?"

"Something has been puzzling me," I replied, "and I thought the walk would give my thoughts an opportunity to put themselves in order."

"It is a day of puzzlements, no? Will you not share your puzzlement with me?"

"Well," I demurred, "it is a small thing -- probably something I did to myself. But I do not wish to intrude on your time."

"Ah, but it is no intrusion for a friend."

"Well," I said as we turned across the Pont Neuf, "as you know I dabble in Perl, and I like to keep a variety of systems available for testing purposes. I upgraded one of these and was re-installing Perl, when one single module failed to install -- indeed, failed to unpack."

Design goals

1. An infrastructure for having “optional” code blocks that can be eliminated prior to execution.
2. Ideally, these code blocks can be toggled by calling code and then eliminated from the execution tree at the OP level.
3. In essence, delegate 100% of the “Speed vs Correctness” concern to the consumer of the code, not the implementer.

Presently implemented using dead-code folding mechanisms.

a();
if( 0 ){ 
   /* code */ 
}
b()

Which becomes

a();
/* noop */
b();

Additionally, this is implemented with perl constant subs so that the if logic is performed at code body compile time, eliminating any run-time penalties from doing the check:

Dear Perl users,

Two weeks ago I mentioned a couple of activities that I found nice to have in the conference. Today I will tell about other things that we already tested during our previous events.

In 2009, at YAPC::Russia in Moscow Alex Kapranov hosted the Game of the Future, where we were trying to predict the future of Perl and related things. There were a few groups that were compiling the future based on probable or improbable events that might happen in a few years, as well as on the known facts. As a result, a mind map was build, which is quite interesting to read today:

What is the future of Perl.pdf

You may find a number of region-specific items there but the funniest thing is that we were considering the YAPC::Europe in Kiev an unlikely event at that time.

I added perlybook.org to 24pullrequests.com. Hopefully we get some pull requests to iron out the issues we have.

Another related project I added is EPublisher-Source-Plugin-PodFromGithub. When we have finished that plugin we would be able to convert stuff like the Perl Advent Calender articles into ebook formats.

Due to private reasons I wasn't able to finish that plugin before December started :-(

24pullrequests.com takes the spirit of the Advent coding calendar and puts a new spin on it. Try to send one pull request per day for the next 24 days and 24pullrequests.com will help you track your progress. At the time of writing, 1,224 devs have already signed up.

Some Perl projects are already represented, but there's still room for more. It would be good to see some more Perl projects on the list for participating Perl devs who are looking for something to contribute to.

I've been exploring the Perl::Critic configuration file somewhat, and something struck me as unusual.

It seems fine for using for the usecase of "inherit some predefined set of rules and apply them selectively", which works fine if you just want to adopt some other standard that is pre-existing, and just make minor adjustments.

However, if you're wanting to create policy sets for others to use, it seems poorly suited.

1. Existing Systems

1.1. Severity level

This feature seems confusing.

It looks simple at first, but its problematic for anyone to utilise this to create a large, custom policy set.

The gist I get of reading it is you specify a severity level in your configuration, and policies that are included with a larger severity number than that are used. ie: Specify severity = 2 and items with severity levels 2,3,4,5, will be applied, while rules with severity level 1 are ignored.

The documentations suggest it might be a good idea to manually override the severity level for a plugin, ie:

Last week at the London Perl Workshop, I gave my first ever talk. 20 minutes on the subject of documentation. I'm pleased to say it went very well, and I've had some fantastic feedback from everyone who saw it.

I thought the wider perl community would appreciate having a look at my slides. As always, it would make more sense to hear me talking - but this gives a good idea as to what the talk is about.

If anyone wants to invite me to speak at exotic locations around the world, I am available ;)

Documentation for Fun and Profit

...some new stuff for perlybook.org I got an error message and needed quite long to find the cause. This was so unexpected too, because I have not done much changes.

The error message I got:

Unrecognized character \xCD; marked by <-- HERE after og->debug(<-- HERE near column 26 at script/../lib/PodBook.pm line 43.

Here is the code:

Who finds the error first?
Ps: dusty screens will make it harder!

Greetings
Boris Däppen

The Dancer repository on GitHub has been moved, from Sukria's own GitHub account to live under the PerlDancer organisation on GitHub.

This has been done to better share administration duties between the core dev team, and enable commit bits to be distributed more easily where needed.

However, this does mean that the old repository URL will no longer work - the repository is now found at:

https://github.com/PerlDancer/Dancer

If you have a checkout of the Dancer repository, you'll need to tell git about the new upstream URL - if you had a commit bit, so had a read+write checkout:

git remote set-url origin git@github.com:PerlDancer/Dancer.git

Otherwise, e.g.:

git remote set-url origin git://github.com/PerlDancer/Dancer.git

If you have a fork of the Dancer repository, similarly you will need to change the upstream location:

git remote set-url upstream git://github.com/PerlDancer/Dancer.git

The Dancer project website will be updated shortly to link to the new repository.

Groups of Items

A sequence is an ordered list of items, whose items aren't necessarily unique. Perl's arrays are sequences of a finite size:

my @sequence = qw/bar baz ban baz baz/;

A set, however, is an unordered collection of unique items. Perl provides native support for sets in the form of the keys of hashes:

my %set1 = map { $_ => undef } qw/foo bar baz/;
my %set2 = map { $_ => undef } qw/bar foo foo baz/; # Same as above
my %set3 = map { $_ => undef } qw/baz baz bar bar foo foo/; # Also same as above

Because sets are unordered, and contain unique items, the sets formed by the keys of the hashes above are identical. Generally sets are used to test for membership:

my %acceptable = map { $_ => undef } qw/foo bar baz/;
die unless exists $acceptable{ $key };

Set::Scalar provides further useful set operations.

Recently I stumbled upon WebRTC. I started looking into this and found some useful libraries on github .

I have been creating some games in Javascript so thought why not use one of these libraries to use some gestures to play a game .