Composite Pattern in PHP

About 2 years ago I was blogging about design patterns in PHP and then I stopped to pursue writing about NoSQL. Those days are over and I’ve decided I’d like to finish my series on design patterns.

Previously I covered all of the creational patterns which are useful with PHP and the majority of structural patterns. One structural pattern I never covered was the Composite pattern and so that’s what I’m covering today. The purpose of this pattern is to allow trees of objects (composites) to be handled interchangeably, regardless of if the node is a branch of a leaf node. What branch and leaf nodes are is revealed below.

Lets use a hard drive as an example, you have directories which you can think of as branches, and you have files, you can think of these as leaf nodes. Branches contain leaves just like directories contain files. Directories and files are both separate entities, but the goal of the composite pattern is have them interchangeable, as always this means they should implement the same interface. Example methods that they both share include updating the owner and group, changing permissions, fetching size, created date or last modified date, etc.

Continue reading

SOLID Principles – Revisited

I recently rewrote an article on APIE, an article I originally wrote over 2 years ago. Now I am going to rewrite another article I wrote 2 years ago on the SOLID principles.

My views on the SOLID principles, have stayed largely the same, however my knowledge of these principles has matured. This hopefully means, I’ll be able to explain each principle in greater detail and be a lot more concise on each subject. I also like to think my writing style has matured and so I’m able to express myself better with less waffling, which is always a plus.

Continue reading

What is APIE – Revisited

You’ve probably heard of APIE. If you haven’t, the most basic explanation is, “APIE is an acronym for the 4 paramount concepts within OOP, namely abstraction, polymorphism, inheritance and encapsulation.”

Each of these concepts is a huge discussion point in its own right, then there’s how they all fit together to form OOP. Many people have written multi-hundred page documents and book explaining these principles in depth and how to make use of them within different programming languages. Needless to say, I’m not going into that detail and I’m solely going to be discussing the language agnostics. By the end of this article, I hope to have explained each of the four concepts, covering a mix of what they are; how you should make use of them and how they all work together to keep you your code clean and human friendly.

Continue reading

MongoDB – Part 10 – Internals and Final Thoughts

It’s taken me a year to write this MongoDB series, admittedly I have had a lot of down time, but this is the finale. One thing I’ve not given much explanation too, is the internals of MongoDB and how it works under, that what we’ll be covering here.

The main internals I want to cover are, how Mongo actually manages it write concerns using locks and how journaling works. After that, I’ll probably ramble on for a bit and have a big emotional climax.

Continue reading