Its get nowhere day here in the Moose-Pen

As previously mentioned, one principle of Complete Programming is the separation of concerns you normally handle simultaneously. In part two I discuss some further consequences of that and how we use version control in CP.

I've just got this CPAN Testers report which says that my module Compress::Huffman had an error due to $minkey not being set to any value on line 176. Tracing this back, it seems to be due to the use of the word 'inf' on line 166, then this being not converted to infinity but to zero for some reason, and $minkey never getting set.

I don't remember where I got the idea to use 'inf' for infinity, but I'm switching over to the method given here of using 9**9**9 instead.

Incidentally, for those interested in the Huffman algorithm, $minkey here is the least probable key, and its probability is $min, which is set to the value of infinity at the start so that every key will have a lower value than it.

I saw a lot of confusion with what should be passed to the native trait when working on binding a C function from a library using NativeCall.

One important thing to remember is Perl 6 trait are solved at compile time. This is important because every value passed to a trait take their compile time value.

use NativeCall;
my $foo = "a";
sub foo is native($foo) {*}

This will fail to compile since native does not take Any has a valid type. Even if $foo can be checked as being a Str, its compile time type is Any. Easy to check with a BEGIN block.

It is go back again day here in the Moose-pen

In my last bunch of posts I though I had finally got all my element view, parentheses and 'AND' ; checking coming out all OK so I started today by going back to here I left off in Driver::DBI. The first thing I did was re-run the test suite and I ran into this

#   Failed test 'Where with function and 1 param SQL correct'
#   at D:\GitHub\database-accessor-driver-dbi\t\lib/Test/Utils.pm line 56.
# Expected SQL--> SELECT people.first_name, people.last_name, people.user_id
 FROM people WHERE length(people.last_name) = ?
# Generated SQL-> SELECT people.first_name, people.last_name, people.user_id
 FROM people WHERE  AND length(people.last_name) = ?

Read this article on Rakudo.Party

While observing a recent split in a large open source community, I did some self-reflection and thought about the state of the Rakudo community that I am a part of. It involved learning of its huggable past; thinking of its undulating present; as well as looking for its brighter future.

This article is the outcome. It contains notes to myself on how to be a better human, but I hope they'll have wider appeal and can improve communities I am a part of.

Part I: Digging a Hole

A lot of organizational metaphors involve the act of climbing. You start at the base of a hill or a ladder and you start climbing. The higher you get, the more knowledge, power, and resources you attain. There's a problem with that metaphor: you're facing the backs of the people who came before you and they're not really paying attention to you.

C comments and regular expressions

The C programming language has two kinds of comments, ones with a start and end marker of the form /* comment */, and another one which starts off with two slashes, //, and goes to the end of the line, like Perl comments. The /* */ kind are the original kind, and the // kind were borrowed from C++.[1]

Let's suppose you need to match the original kind of C comments. A simple regex might look something like this:

qr!/\*.*\*\/!

Here we've escaped the asterisks in the comment with a backslash, \, and used exclamation marks, !, to demark the start and end of the regex, so that we don't have to escape / with a backslash.

However, C comments have the feature that they can extend over multiple lines:

/*
  Comment
*/

I was handling some bad Markdown input using Text::Markdown, when I saw it generate broken HTML.

I started with (bad) Markdown input " 1. z\n >" and got back HTML <p><ol>\n<li>z</p>\n\n<blockquote>\n <p></li>\n </ol></p>\n</blockquote>.

(See the incorrectly nested HTML tags, <p><ol><li></p>?)

So I tried feeding this bad Markdown to four different Perl Markdown libraries: Text::Markdown, Text::MultiMarkdown, Text::Markdown::Discount, and Markdent, to see which one would give me valid HTML.

The results?

• Text::Markdown — invalid HTML <p><ol>\n<li>z</p>\n\n<blockquote>\n <p></li>\n </ol></p>\n</blockquote>\n

• Text::MultiMarkdown — invalid HTML <p><ol>\n<li>z</p>\n\n<blockquote>\n <p></li>\n </ol></p>\n</blockquote>\n

• Text::Markdown::Discount — valid HTML! <ol>\n<li> z\n\n<blockquote></blockquote></li>\n</ol>\n\n

• Markdent — valid HTML, but doesn't generate a simple HTML fragment <!DOCTYPE html>\n<html><head><title></title></head><body><ol><li>z\n &gt;\n</li></ol></body></html>

The solution? Switch from Text::Markdown to Text::Markdown::Discount.

It test review day again here in the Moose-Pen

Today I was having a look at coverage that the '58_parenthes.t' test case gives and with only seven tests it is rather sparse, time to add a few more in.

What I want to first improve is the coverage for 'functions' and 'expressions' to make sure the nested nature or the left and right attributes are correct. I started with this formula 'element' make up of a number of 'expressions','functions', 'params' and 'elements' that use parentheses;

(abs((People.salary + .05) * 1.5))*People.overtime+(abs(People.salary+.05) *2)*People.doubletime)

Sometimes we are required to check incoming IDs not only for format, but also for existence in DB.

But different IDs we should check through different models.

This pull request tries to add this functionality. If it will be appiled you can do next:

$v->required( 'invoice_id', [ data_exists => 'Invoice' ] );
$v->required( 'order_id', [data_exists => 'Order' ] );

And the fileter:

Hey everyone,

Following is the p5p (Perl 5 Porters) mailing list summary for the past week.

Enjoy!

We have uploaded videos from this year's workshop to YouTube: Swiss Perl Workshop on YouTube.

Note that we didn't record all talks as some were given at TPC and will be of much better quality from them. Also we didn't record the workshops, nor the lightning talks. Still, we have some exclusive content, so have a look.

It is fix a bracket and AND day in the Moose-pen

Rakudo and other repositories in perl6 GitHub org have plenty of open bug tickets. We decided it would be neat to give them an extra push with concentrated effort, which is why we'd like to organize a monthly, 1-day virtual event where we pick a repository and everyone works on open tickets in that repository.

The day will be first Saturday of every month. This month we'll be hacking on the Issues of github.com/perl6/doc repository.

Whether you're a seasoned Rakudo developer or just starting out, join us this Saturday in #perl6 on irc.freenode.net chat channel (no specific time) and contribute! If you'd like to simply hang out, you're welcome too, we love company!

See also: our SQUASHathon Wiki or talk to a human about this.

The latest release of Test::podimage, version 0.05, shows a few interesting experimental ways to include images in CPAN modules.

It seems there is a way to show image files from the distribution on metacpan by using a leading slash, which I'd never heard of until now. There's also a new "=for image" tag. Oddly enough, although this was proposed five days ago, the CPAN grep search site tells us that this tag actually appears in some CPAN modules such as this one from 2010, although the above don't actually display on metacpan, perhaps because there is no leading slash in the image name.

A data URL can also be used.

Most of the image formats don't work on search.cpan.org.

Problems with concurrency, a post from the hard reality.

This worries me a bit I must admit; a few years ago, before the official release of P6, I tried my hand at concurrent programming in rakudo and it was so broken that i simply shelved P6 for over a year, it was simply not ready for a lambda dev like me. I would have loved to be in the trenches but I did not have the time to fight with core dumps.

As the speed of P6 is not stellar, I believe many of us, lambdas, will try to run things in parallel, it's also fun, to make them more attractive. The concurrency mechanism in P6 look good on paper, good enough so I can find myself dreaming of throwing in a few keywords in places I think concurrency would make a difference.

There is a nice silver lining to this one, It took a very short time before a lead developer answered me. I believe his answers may be interesting to read.

A description of the problems I encountered is here: gist

It condiment day again here in the Moose-Pen

Time to do some more catch-up coding as my most recent round of changes to fix all my 'element->view' woes I ended up removing any checks for 'parentheses' I had in place. To recap on the original idea of the parentheses check was to make sure that there was at least one closing bracket for each opening bracket in the 'conditions' being send down to the DAD.

As it stands now I am using the '_parentheses_check' sub to check all the attributes that that may contains not just an 'element' but any class that can use a 'predicate' so 'Elelemets','Functions','Expressions' and 'Conditions' quite an expended set.

Unfortunately I can not really test to see that the positioning of the brackets are syntactically correct as this;

  ORDER BY (left(test,12)+12)*12

During my last post I mentioned the method of Complete Programming, which started as my knee jerk reaction to the insanities of waterfall and XP. I'm not really big on manifestos but writing down things helps to think clearly and so you might also benefit from thinking about one important principle in CP.

This module offers a way to check your web pages for correct gzip compression. It not only checks that your web page is compressed properly when required, but also checks that the web page is not accidentally compressed when not required, and that the compression actually does something useful in terms of reducing the page size. I wrote it because I couldn't find anything to do that on CPAN.

It's compatible with Test::More if you want to run the compression checks automatically.

We recently did an interview with Daisuke Maki on the Perl community in Japan.

This is what came out of it - http://blog.builtinperl.com/post/perl-in-japan.

Have a look/read.