speaker: Chad 'Exodist' Granum

The DCI concept was created by Trygve Reenskaug, (inventor of MVC) and James Coplien.

DCI Stands for Data, Context, Interactions. It was created to solve the problem of unpredictable emergent behavior in networks of interacting objects. This problem shows itself in complex OOP projects, most commonly in projects with deep polymorphism. This is a problem that Procedural/Imperative Programming does not have.

DCI does not replace OOP, instead it augments it with lessons learned from looking back at Procedural Programming. It defines a way to encapsulate use cases into a single place. This provides an advantage to the programmer by reducing the number of interactions that need to be tracked. Another advantage is the reduction of side-effects between contexts.

Another way to look at it is that a DCI implementation is much more maintainable as a project matures. Changes to requirements and additional features cause clean OOP project to degrade into spaghetti. DCI on the other hand maintains code clarity under changing requirements.

You will Learn:

• How to think in DCI
• How the DCI cpan package helps you write DCI
• That you may already write things in a form of DCI
• How a DCI implementation compares to an OOP implementation (in a generic task)

As usual, the meeting will be followed by social hour at the Lucky Lab.

speaker: round table

A "Perl with Objects" round table. We'll examine usage and issues with class composition, performance, and compatibility with various lighter-weight alternatives.

• Mouse vs Moose vs Moo, when to use which? – Schwern
• Moose, Mouse, and Moo performance – Dana Jacobsen
• Zeus and Contradictory.pm – Eric Wilhelm
• Reindeer – Chris Weyl
• MOP in the core – O_o

As usual, the meeting will be followed by social hour at the Lucky Lab Brew Pub.

Ray tracing is an algorithm for generating 3D images and involves tracing rays of light around a virtual scene. Ray tracing is more computationally intensive than rasterization (which is used for video games) but is better at capturing phenomena like reflection and refraction. A simple raytracer can be written in a day, while complex ones requires advanced physics equations and statistical techniques. In this 90-minute talk, we'll cover enough material for you to build your own raytracer, and some more advanced features you could add to continue developing. Ray tracing lends itself to object-oriented programming so we'll also get some practice with typescript.

Presented by PDX Code Guild Instructor Matthew Cooper