A while ago, I covered The Observer Pattern, a really useful pattern, particularly when it comes to event-handling systems.
Today, I’m going to take a look at the Composite Pattern, another really useful pattern that allows you to treat individual objects and collections of those objects as if they were the same. That may sound a little strange, but we’ll look at a concrete example, which should help clarify things: a List-based system.
The Observer Pattern is probably one of my favourite patterns.
It’s fairly straightforward, flexible, and best of all, the base classes you need to implement the Observer Pattern are available in the Standard PHP Library, so it should be available to all PHP5 applications.
Let’s jump straight in, and take a look at a possible scenario where we could use this pattern.
No need to elaborate much on this one. Here are ten very useful functions for manipulating strings. Some are very simple and straightforward, but are still very useful.
I would normally use these in class called something like
Common_Strings, and make each function
static but I’ll just provide them here as functions for you to use as you please.
At the recent PHP UK Conference in London, one speaker described the Singleton Pattern as being evil. The main point brought up was that it brought global variables in through the back door, including all the problems associated with them.
Well, this is true, but only to a point. Just like eating ice-cream or junk food all the time would be bad for you, so would relying on the Singleton Pattern. However, it is still a very good pattern when used in specific instances, and when used sparingly, with discipline.
So, when could we consider using it?
Okay, I’ll admit: comments are not an exciting topic for most programmers. They generally aren’t viewed by anyone else except other coders, and if we’re honest, most coders ignore them, either by folding them up in their IDE, or by skipping over them. This is normally because coders don’t think about their comments in the same way as they think about their code.
So here are the tips I’ve come across over time that have helped me make better use of comments.