PHP

A parabolic curve is a type of curve where every point is an equal distance from a focal point. There a number of different way to generate this sort of curve using math, but one of the simplest is to use straight lines to create the illusion of the curve.

The curve is created by diving two axis into equal points and then drawing a line from the first point on one axis to the last point on the opposite axis. Each line of the curve is drawn in the same way, repeating the process of drawing a line between opposite points for every point along the axis.

I quite like the end of the year report from Spotify that they call "Wrapped". This is a little application in which they tell you what your favorite artist was and what sort of genres you listened to the most during the year. It shouldn't come as a surprise to me that I listened to this or that, but since I listen to Spotify around 30-40 hours a week I certainly lose track of what my favorite artist was that year.

This years report got me thinking about how difficult it would be for me to generate my own Spotify report, whenever I wanted. Maybe to see who I had listened to the most during the week, or what sort of genres I was into at the moment.

Let's say you had a class that you wanted to use, but there was some sort of error in creating the object. This might be that the wrong parameters were passed, or the third party service (eg. a database) wasn't available at the time of creation.

If this happens you'll obviously want to handle the error correctly, but the question is would you throw an exception in the constructor or handle the error condition elsewhere?

Note that this article will talk about PHP, but the same discussion applies to other languages that implement OOP principles.

 Question

What does the following code print out?

function arrayPrint($array)
{
   echo implode(' ', $array);
}

$arrayA = [1, 2, 3];
$arrayB = $arrayA;
$arrayB[1] = 0;
arrayPrint($arrayA);

Using frameworks to handle the authentication of your PHP application is perfectly fine to do, and normally encouraged. They abstract away all of the complexity of managing users and sessions that need to work in order to allow your application to function.

That said, it is important to take a step back and understand how authentication works in PHP. This allows you to more accurately debug problems with framework authentication systems that you make common use of.

Creating an authentication system using PHP is pretty simple since PHP has many of the features and functions built in. In fact, frameworks will simply wrap this feature set into a coherent authentication model that can be expanded to introduce new features.

In this article I will go through the steps required to create an authentication system using PHP and MariaDB. I will assume you have some knowledge of PHP, but that you want to know more about how to authenticate users.

A sparkline is a very small line graph that is intended to convey some simple information, usually in terms of a numeric value over time. They tend to lack axes or other labels and are added to information readouts in order to expand on numbers in order to give them more context.

Sparklines tend to be around 20-30 pixels height and up to 150-200 pixels wide. The are generally best when you want to show between 5 and 15 items as adding more items to such a small graph can make things a little messy.

I read The Daily WTF every now and then and one story about bad logging code in PHP stood out to me. The post looked at some PHP code that was created to log a string to a file, but would have progressively slowed down the application every time a log was generated.

PHP is a great language as it allows you to put together code without easily shooting yourself in the foot. One downside of this ease of access is that it can allow beginners to put together code that works, but will ultimately cause problems in the long run. The PHP code given in the post is certainly an example of this.

I know that the goal of The Daily WTF isn't to fix problems found in code and is more of a satirical look at bad coding examples. I thought, however, that it would be good to look at the code and fix the issues it had.

If you've ever looked at the settings in a digital camera, or have experience with image processing programs like GIMP, then you may have seen a colour histogram. This is a simple graph that shows the amount of different shades of colour are present in the image.

They are created by looking at the number of colours in a given image and them mapping their red, green and blue values against a the frequency of their occurrence in the image.

Colour histograms are useful for looking at the overall colour distribution within an image and can also be used to simplify the colours of an image by restricting how much of a certain colour is allowed based on its frequency.

I was writing unit tests for a API mapping function recently and came across this interesting issue. The code I was writing tests for was in a legacy codebase that I was making changes to, and it made sense to have some unit tests in there before I started work to ensure everything worked before and after.

The mapping function in question would take a value as input and return another value as the output. The code seemed like it should work, but then applying certain values to the mapping function it would produce an incorrect result.

Embedding image within pages of content helps both within the design of the page and when shared on social media. If you set up meta tags to point at a particular image then that image will appear when the page is shared on social media. This makes your page stand out more.

A while ago I added a header image to the articles in the form of a field that references a media item, which is quite typical when adding images to pages. To add an header image to an article I just had to upload an image and Drupal would handle the size, placement and meta data for that image.

With the field in place, however, I spent a while adding a default header image to new articles so I haven't been making good use of it. My GIMP skills aren't that amazing and so the prospect writing an article and spending time fiddling with text elements on an image every week wasn't that appealing.