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Tue, 10 Apr 2012

Perl 6 Hackathon in Oslo: Be Prepared!


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The Oslo Perl Mongers invite to the Perl 6 Patterns Hackathon in Oslo. I have previously suggested that we hack on database connectivity, and so far only got positive feedback. If you want to help, here is what you can do to be prepared:

  • Get a github account
  • Build and install Rakudo
  • Build and install zavolaj/NativeCall
  • download MiniDBI
  • install and prepare databases to talk to

To hack efficiently on those projects, and to benefit from last-minute fixes, you should obtain Rakudo, NativeCall and MiniDBI from their git source repositories -- that last release is already outdated.

Here are the instructions in detail. If at any point you run into problems, feel free to ask on the #perl6 IRC channel or the perl6-users@perl.org mailing list.

Get a Github account

All the interesting Perl 6 code lives in git repositories on github. If you don't have an account already, sign up -- it's free.

Build and install Rakudo

This step is described well on the Rakudo homepage. Please follow the instruction in section "Building the compiler from source".

For the following steps it is important that you have a fresh perl6 executable file in your $PATH. If you have downloaded rakudo to /home/you/p6/rakudo/, you can run the command

PATH=$PATH:/home/you/p6/rakudo/install/bin

(and put it in your ~/.bashrc file if you want it permanently available, not just in this shell).

Build and install zavolaj/NativeCall

NativeCall.pm is the high-level interface for calling C functions from Perl 6 code. Install it:

$ git clone git://github.com/jnthn/zavolaj.git
$ cd zavolaj
$ cp lib/NativeCall.pm6 ~/.perl6/lib/

If you download and install ufo, you can use it create a Makefile for zavolaj. Then you can also run make test. On Linux it might not find the test libraries (which is mostly harmless, because you usually call libraries that are installed into your operating system, like those from mysql or postgres). In this case you should run LD_LIBRARY_PATH=. make test instead.

Download MiniDBI

That's not hard at all:

$ git clone git://github.com/mberends/MiniDBI.git

Install and Prepare Databases

So far, MiniDBI has (somewhat limited) support for mysql and postgres. Since it is always easiest to start from (at least somewhat) working code, I strongly recommend that you install at least one of those database engines.

Most modern Linux systems allow an easy installation via the package manager, and there are installers available for other operating systems. Be sure to also install the headers or development files if they come as extra packages.

Mysql

As mysql root user, run these statements:

CREATE DATABASE zavolaj;
CREATE USER 'testuser'@'localhost' IDENTIFIED BY 'testpass';
GRANT SELECT         ON   mysql.* TO 'testuser'@'localhost';
GRANT CREATE         ON zavolaj.* TO 'testuser'@'localhost';
GRANT DROP           ON zavolaj.* TO 'testuser'@'localhost';
GRANT INSERT         ON zavolaj.* TO 'testuser'@'localhost';
GRANT DELETE         ON zavolaj.* TO 'testuser'@'localhost';
GRANT LOCK TABLES    ON zavolaj.* TO 'testuser'@'localhost';
GRANT SELECT         ON zavolaj.* TO 'testuser'@'localhost';

Postgres

Launch psql as the postgres user and run these statements:

CREATE DATABASE zavolaj;
CREATE ROLE testuser LOGIN PASSWORD 'testpass';
GRANT ALL PRIVILEGES ON DATABASE zavolaj TO testuser;

You should now be able to connect with:

psql --host=localhost --dbname=zavolaj --username=testuser --password

(psql will ask you for the password. Enter testpass).

Other Databases

If you want to work on a backend for another database, it helps to have that database installed. Sqlite is an obvious choice (easy to install, zero setup), but of course there are other free database too, like firebird.

Project ideas

There is a lot of stuff to do. What follows is only a loose, incomplete collection of ideas.

  • Fix the postgres backend to actually pass its tests
  • Both mysql and postgres backends don't implement placeholders properly; change them (or one of them) to pass the placeholder values out of band.
  • Write an sqlite backend
  • Currently the user builds a DSN ("data source name") string out of the driver name, database name, db host name and so on, and then the driver parses it again. One could change that to pass all the information as named parameters instead.
  • Improve test coverage. For example test that numbers round-trip with the correct types.
  • Write a small application that uses a database. That's the best way to see if MiniDBI and the backends work.

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