Today I am d going to start filling in my API a little and some might remember the table from this
post
looking at it a second time I think I need to make a few adjustments to this
+-------------------+-----------------+-----------------+
| Data Accessor | SQL | Mongo |
+-------------------+-----------------+-----------------+
| Param | Param | Param |
| Element | Field | Name Value Pair |
| Predicate | Predicate | Options |
| View | Table (or view) | Collection |
| Condition | Where | Find |
| Link | Join | Lookup |
| Gather | Group | Aggregate |
| Filter | having | ? |
| Sort | Order | Sort |
+-------------------+-----------------+-----------------+
Just so I updated the table to link the 'Condition' to the where clause in SQL and Find in Mongo, and just as a reminder here it is again;
Condition
A logical Predicate supplied to the target database by the Data Accessor to filter data.
Now it makes no sense to have just one condition on a query so this should be a collection of some form so I think I have to redefine this attribute as
Conditions
An Arry-Ref of logical Predicates supplied to the target database by the Data Accessor to filter data.
And in my code I added
[This is a post in my latest long-ass series. You may want to begin at the beginning. I do not promise that the next post in the series will be next week. Just that I will eventually finish it, someday. Unless I get hit by a bus.
IMPORTANT NOTE! When I provide you links to code on GitHub, I’m giving you links to particular commits. This allows me to show you the code as it was at the time the blog post was written and insures that the code references will make sense in the context of this post. Just be aware that the latest version of the code may be very different.]
Last time I rearranged our UI to be (hopefully) a bit more intuitive. This time I want to clean up the remainder of those pesky CPAN Testers failures on our way to the next solid release.
Well for today’s post I am going to continue along with one of the basic building blocks of a good Moose program coercion. We saw in the last post how I started to clean up my interface with coercion and I am going to do that to the next
Accessor.pm
attribute
has elements => (
isa => 'ArrayRef',
is => 'rw',
);
Welcome to the Perl 6 Hands-On Workshop, or Perl 6 HOW, where instead of
learning about a specific feature or technique of Perl 6, we'll be learning
to build entire programs or modules.
Knowing a bunch of method calls won't make you a good programmer. In fact,
actually writing the code of your program is not where you spend most of
your time. There're requirements, design, documentation, tests, usability
testing, maintenance, bug fixes, distribution of your code, and more.
This Workshop will cover those areas. But by no means should you accept
what you learn as authoritative commandments, but rather as reasoned tips.
It's up to you to think about them and decide whether to adopt them.
Project: "Weatherapp"
In this installment of Perl 6 HOW we'll learn how to build an application
that talks to a Web service using its API (Application Programming Interface).
The app will tell us weather at a location we provide.
Sounds simple enough! Let's jump in!
One of my tasks when I'm not working or writing Perl code is to keep the
finances of the Frankfurt Perlmongers e.V. club in order.
Part of this is doing the taxes but a more important part is to pay the
incoming invoices in time and to keep all the receipts for this in order.
As we do most transfers electronically, it was a long-term goal for me to
provide the board with an automated monthly account statement.
Docker is quite popular solution to rapidly spin up developers environments. I have been playing with it and it seems fun for me. The other fun thing I found that Sparrow could be a good solution to build up new docker images.
Here is short example of how it could be. A few lines in Dockerfile and you have a GitPrep server up and running as docker container. Whew!
So today, to start the new year right, I really am going to have a look at Moose coercion which I have been promissing to do since this
post
. So to refresh your memory I had created my
types
role and one type and added it to my accessor like this
has view => (
is => 'rw',
isa => 'View',
);
So what exactly does coercion do for us? Well as I had illustrated in a early post what I want it to do it take an input hash and then create an object from that hash to save us from typing up such unsightly things as
fREW's article on using it, although the specific setup refers to a previous repository that can still be cloned but it's probably not maintained any more (not reachable from Github's portal, anyway);
Currently rakudo.js is at the point where: node rakudo.js --setting=NULL -e 'use nqp; nqp::say "Hello World"'
works but node rakudo.js -e 'say "Hello World"' doesn't.
What's needed for the later is to get rakudo.js (Rakudo compiled to JavaScript) to compile the setting
The general work-flow for that is:
Try to compile the setting with rakudo.js.
While rakudo.js is compiling some error appears.
I then figure out wheter it's a result of a missing feature or some bug in the js backend.
I implement the feature and write tests for it or fix the bug.
I then repeat the process.
Lather, rinse, repeat.
Until the setting compiles Rakudo.js is not yet usable by users.
Even getting something very simple like say "Hello World" requires a fair chunk of the setting to work.
The rakudo specific work is done in the js branch of rakudo https://github.com/rakudo/rakudo/tree/js.
Most of the work on the backend itself is done in the master branch in the nqp repo.
I recently wrote about Veure's test suite and today I'll write a bit about how we manage our database. Sadly, this will be a long post because it's a complicated problem and there's a lot to discuss.
When I first started Veure, I used SQLite to prototype, but it's so incredibly limited that I quickly switched to Postgres. It's been a critically important decision, but I want to take a moment to explain why.
All software effectively has four "phases" which amount to:
Initialization
Input
Calculation
Output
Note that we could rewrite the above as:
Initialization of data
Input of data
Calculation of data
Output of data
Notice a pattern?
Yeah, I thought so. There are all sorts of areas where we could get things wrong in software, but the further down the stack(s) you go, the more care you need to take because the more damaging bugs can be. Data storage is often pretty low in your stack and you don't want to get this wrong. So what happens?
Well off track again. So I am not going to do my bit on coercion today after all. If anyone out there was actually downloading my code and running my tests you might see this;
Load of Database/Accessor/DAD/Types.pm failed:
Error=Can't locate Database/Accessor/DAD/Types.pm in @INC (@INC contains: D:\GitHub\DA-blog\lib D:\GitHub\Replay\lib C:/Dwimperl/perl/site/lib C:/Dwimperl/perl/vendor/lib C:/Dwimperl/perl/lib .) at (eval 378) line 2.
Database/Accessor/DAD/Types (Database::Accessor::DAD::Types) may not be an Database Accessor Driver (DAD)!
Back in the day, I wrote Perl 5 module
Number::Denominal that breaks up a number into "units," say, 3661 becomes '1 hour, 1 minute, and 1 second'. I felt it was the pinnacle of achievement and awesome to boot.
Later, I ported that module to Perl 6, and recently I found out that Perl 6
actually has .polymod method built in, which makes half of my cool module entirely useless.
Today, we'll examine what .polymod does and how to use it. And then I'll
talk a bit about my reinvented wheel as well.
Denominated
The .polymod method takes a number of divisors and breaks up its invocant
into pieces:
While playing with docker I created a simple sparrow plugin to install docker engine on Ubuntu Trusty 14.04 (LTS) - https://sparrowhub.org/info/docker-engine . Please let me know if other platform to support you need! ;))
Now to get back on track to what I wanted before I made a little Boo-Boo, So in today's post I am going to have a quick look at Moose and its Coercion abilities. One thing about moose Coercion is it works along with Moose Types so you can't have one without the other.
So lets start wit the Accessor.pm 'View' attribute.
Right now we have this
has View => (
is => 'rw',
isa => 'Object',
);
Which is fine but there is noting stopping my from entering any type of object in there so lets fix that
Much of what I do involves retrieving stuff over the HTTP family of protocols.
My go-to solutions are either the APIs of LWP::UserAgent/WWW::Mechanize
or the API of AnyEvent::HTTP, depending on whether I want some kind
of concurrency or not. Since I found Future as a somewhat nicer way of
structuring callback hell a bit differently, I've looked around for a nice
implementation of a HTTP client that works with various backends and maybe
even without a backend.
DISCLAIMER: data theft is a serious crime in many jurisdictions. The author does not condone or encourage anyone to break laws. The information provided here is for educational purposes only.
PART I: Anguish: The Invisible Programming Language
You may be familiar with funky esoteric languages like Ook or even Whitespace. Those are fun and neat, but I've decided to dial up the crazy a notch and make a completely invisible programming language!
I named it Anguish and, based on my quick googling, I may be a lone wolf at this depth of insanity. In this article, I'll describe the language, go over my implementation of its interpreter, and then talk about some security implications that come with invisible code.
The Code
Here's an Anguish program that prints Hello World:
