Today in the Moose-Pen I am going to look at something new 'Native Delegations' on attributes or to say it another less wordy way 'Traits'
Native Delegation
is a way to let you treat standard Perl data structure as if they where objects. So to take an example from my test cases say you have this
foreach my $index2 (0..(scalar(@{$predicates[$index]->predicates()})-1)) {
that (scalar(@{$predicates[$index]->predicates()})-1)) is not very readable. Now suppose we could just have this
i'm using padre editor with strawberry perl bundled in
dwimperl
i have multiple files open, then when i click on one of the
tabs to close 1 file, padre crashes without an error message,
the application just closes.
this also happens when i save the session.
kinda frustrating.
do you discuss padre here or am i in the wrong forum?
thank a bunch in advance
Imagine you were playing with Perl 6 and you came across a buglet
or you were having some fun with the Perl 6 bug
queue—you'd like to debug a particular core
subroutine or method, so where's the source for it at?
Asked such a question, you might be told it's in Rakudo compiler's
GitHub repository. Depending on how deep
down the rabbit hole you wish to go, you may also stop by NQP's
repo, which is a subset of Perl 6 that's used
in Rakudo, or the MoarVM's repo, which
is the leading virtual machine Perl 6 runs on.
The answer is fine, but we can do better. We'd like to know exactly where
da sauce is.
Stick to The Basics
The most obvious way is to just use grep command in the source repository.
The code is likely in src/ directory, or src/core more specifically.
We'll use a regex that catches sub, method, and multi keywords. For
example, here's our search for path sub or method:
We recently came across Pegex and found it to be an interesting module for parsing text data. Instead of using regular expressions directly, the user can write a grammar for the data to be parsed. The data can be automatically converted to a native Perl object or, if the user desires, it's possible to use actions to handle the grammar while parsing using a Pegex::Receiver class.
Pegex uses the type of grammars called Parsing Expression Grammars (PEG), which is an unambiguous form of writing a grammar. Each parsed string will in effect have a single valid parse tree. Since Pegex converts the rules of the grammar to regular expressions, it is a greedy parser.
In this blog post we demonstrate how to easily use Pegex to parse an /etc/hosts file on Linux and convert the result into Perl objects automatically without having to manually create any object.
For more details check out the original blog post by me here.
Well more testing and re-factoring with just a little Moose in the Moose-Pen today. So I spend a good deal of time getting my tests cases all in a row. Now just a few interesting details on that, I created a number of generic utility tests that can be reused in my test cases. What I did was take the 'cmp_deeply' test like this on in
33_constants.t
Since the Perl Magazine sadly had to close i didn't wrote as many Perl articles anymore. Because I miss it sometimes I recently agreed to write for DZone. Its a Java- centric site with many light weight pieces. I read it myself, since you can find interesting stuff here and there.
But why I'm writing this here? In order to publish, it has to be transported from your blog. And since I don't own another blog and the Perl 6, Perl 5 and software engineering stuff I want to write about fits here nicely : I will use this blog as transport. for that purpose. So please don't wonder if some of my next text are here sound like I assume you never heard about Perl. If the entry is marked with the category DZone you know why.
But there is also another reason why I use this Blog. Since I will be a kind of press secretary for Perl in that area, I actually want to be controlled and corrected by you and also encourage you to engage in the discussions below these articles on DZone (link will be provided in comments), to make Perl more visible to outside world.
Well it clean-up and re-factor day in the Moose-pen. So no new Moose Majick today just cleaning up and adding in stuff that I have left out (forgotten actually) and moving things about.
Well the first thing I did was finish off the last three of my remaining Accessor attibutes, 'gathers', 'filters' and 'sort' or if you are SQL inclined 'group by', 'having'. and 'sorts'.
The 'gathers' and 'sorts' attributes are just a pair of 'ArrayRefofElements' which I covered off in this post and types and the 'filters' is a 'ArrayRefofConditions' which I covered in this post. I did of course spend a little time making sure that my DAD role attributes matched up with the accessosr ones and as this is me programming I created two new test cases, 37_gathers.t that handles filters as well, and 39_sorts.t
While testing a fix for one of the Less Than Awesome behaviours in standalone
Signature objects, I came across
a bugglet. Smartmatching two Signatures throws, while spilling a bit of the
guts:
<Zoffix> m: my $m = method ($a: $b) { }; say $m.signature ~~ :($a, $b);
<camelia> rakudo-moar 46838d: OUTPUT«Method 'type' not found
for invocant of class 'Any' in block at line 1»
So I figured I'll write about fixing it, 'cause hacking on internals is lots of
fun. Let's roll!
Golf It Down
The less code there is to reproduces the bug, the fewer places there are
for that bug to hide. We have a detached method and then we smartmatch
its signature against something else. Let's try to golf it down a bit
and smartmatch two Signatures, without involving a method:
So today in the Moose-pen I am going to move onto something a little differtn and that is my Accessor 'links' attribute which I am going to cover with the 35_links.t test suite.
I did a quick review of the bits and pieces I had stubbed in so far and I notices I need a few thing. First had a look at my Accessor 'links' attribute and I will need a new type for that. So to get this new 'ArrayRefofLinks' type I just did what we have seen in a number of older posts, namely add in a 'use', a 'class_type' and a 'subtype' into my Types.pm, I will hold off on a coercion for now till I get a little deeper into my post. So that takes case of 'links'.
I also noticed that 'Links' attribute of my DAD now had the wrong type as well so that was change to the 'ArrayRefofLinks' type
Looking at my 'Database::Accessor::Link' class I have never liked this two attributes
Today in the Moose-pen I am going to play with the very familiar 33_condtions.t and this time I am going to solve another little API problem I know I am going to run into.
Part of my evil plan is to allow end users to add in conditions on the fly and I have made provision for that with the 'rw' 'conditions' attribute found on my DAD Role. Now I have to fix a minor oversight on my part can change the type on 'conditions' to be the same as the original in Accessors, so I changed this
– isa => 'ArrayRefofPredicates',
++ isa => 'ArrayRefofConditions',
What I want to be able to do is allow my end users to do something like this
I wrote my first Perl 6 program—a New Years IRC Party bot—around Christmas,
2015. The work included releasing the IRC::Client
module, and given my
virginity with the language and blood alcohol level appropriate for the Holiday
Season, the module ended up sufficiently craptastic.
Recently, I needed a tool for some Perl 6 bug queue work, so I decided to lock
myself up for a weekend and re-design and re-write the module from scratch.
Multiple people bugged me to do so over the past months, so I figured I'd also
write a tutorial for how to use the module—as an apology for being a master
procrastinator. And should IRC be of no interest to you, I hope the tutorial
will prove useful as a general example of async, non-blocking interfaces
in Perl 6.
I've started a new series on my testing blog about the differences between Perl, Python, and Ruby's testing ecosystems and architectures. First article looking at the most basic assertions is done:
