PHP

When creating regular expressions for PHP I tend to use the awesome tool PHP Live Regex.

This tool has really helped me over the last couple of years to create regular expressions for many of the projects I've been working on. Everything from validation functions to formatters that use regular expressions have had their expressions worked out using this tool. I even use it for testing one off expressions where I just need to find/replace in a file.

In December 2015, PHP 7 introduced scalar type declarations and with it the strict_types flag. This flag can be used to enforce the type of value passed to functions. Although I have seen it in action in the past, I have never actually used it before so I decided to look into it a little to see what it was about.

For some background, types are not strictly enforced in PHP. This means that it is not only possible to swap the type of a variable from one type to another, but it is also possible to swap a variable of one type to another depending on the context being used. Programmers getting started in PHP will spot this when attempting to print out a boolean value as this will be cast to an integer before being printed out. This means that when attempting to print 'true' PHP will instead print out '1'. PHP will automatically coerces values to be one type to another when passing values to functions.

The instanceof operator in PHP is great at making sure you are looking at a type of object before acting on it. Whilst it's straightforward to use on its own, using it can lead to some undesirable side effects.

As a basic example, let's create a couple of interfaces and classes to show the instanceof operator in action. Rather than just have some test names I am using object names that you might find in a system. This consists of User and Order that might form part of a commerce system.

interface UserInterface {}
class User implements UserInterface {}

interface OrderInterface {}
class Order implements OrderInterface {}

If we instantiate the User object we can detect if the user is an instance of the class User like this.

Steganography is the practice of placing a secret message inside another message and only by looking at the original message in a different way can the hidden message be seen. This might be as mundane as writing a page of text and hiding a message in the text using the first letter of every sentence. Only by collecting the first letter of each sentence together can the hidden message be seen and read.

Modern steganography is defined as hiding a message (or file) inside a file. For example, you might look at an image and see an image, but if a message has been hidden you would also be able to extract it if you know where to look.

I finished my last post on sorting colours using PHP looking at incorporating all three dimensions into the display of the colours. This lead to some interesting displays of colours in discs using different shapes or lengths as an indication of the colour in question. It was still lacking actually rendering out the third dimension in any meaningful way though.

As I am essentially looking at three dimensional data I thought about displaying the data as a cube in a 3D engine. I could then map the three dimensions of colours (red, green, blue) into the three dimensions of the 3D engine (x, y, z). This means creating a 3D scene with random colour data and rendering that scene out. Funnily enough, there aren't a lot of people writing 3D rendering engines in PHP so I looked into writing a very basic version that would just show point data.

I was looking at a media player on my phone the other day and was watching the waveform of the music shown on screen. This was a simple indication of the progress through the track and appeared to show quiet and loud sections of the track I was listening to. This got me thinking about how to extract this information as the media player I was watching must do this in real time in order to actually play the data, not just render this representation of the music.

After a bit of research into the MP3 file format I found that the file format is complex, but straight forward enough to process, so I decided to try and extract the data using PHP. I have seen a few techniques to extract the data from MP3 using PHP, but these largely involve applications like ffmpeg to convert the audio format into something like a WAV file, which is then processed.

I have been adding to my custom Deployer scripts for a number of months and I have now been using it to do more than just deploy my sites. Since it acts as a connection to my website server I have been using Deployer to perform other tasks like creating backups and clearing Drupal caches without having to log into the server to do it. What has helped me here is that I have set out my deployment tasks in a very modular fashion, so although my deployment runs a database backup, I there is nothing to stop me running the database backup command on it's own without doing a full deployment.

So far in this series of posts we have looked at detecting key presses from the user and creating a game of tic tac toe using PHP and the command line. The next step is to create a game that has graphics and real time user input. As we are using the command line we don't have much space to work with so the graphics we create aren't going to be very detailed. The simplest action game I could think of is snake. It has a few simple rules, can have very basic graphics and doesn't involve any physics or other mechanics that would effect the game as a whole. In fact the game snake dates back to the 1976 game Blockade, which was created using just text strings.

Following on from my last post about creating a command line game in PHP we now have a mechanism to listen to keypresses. The next step from here is to create a simple game. After thinking about a game that would fit into the command line I decided that something simple like tic tac toe (also called noughts and crosses) would be a good starting point. The game board is small and the conditions for winning are pretty simple to understand.

I was watching a documentary about old computers on YouTube recently and it showed a video of an early computer game creating using the command line. This wasn't a text based adventure game, but a game creating using text for the graphics running as a program on the command line. This got me thinking that creating something like this should be possible using PHP. If it was possible on a 30 year old computer then surely it's possible to get PHP to do it, right? I thought it might be interesting to create a series of posts showing how to put this together.