This month we study the Singleton Design Pattern, but with a twist. We start with a correct implementation but get it wrong by refactoring. We’ll examine the PHP generated code, each step of the way, to understand what went wrong. We’ll observe at least two reasons the Singleton Design Pattern is now considered an anti-pattern. We’re preparing to learn useful variations next month by seeing precisely how it works under the hood.

The PHP compiler/interpreter reads through our PHP code and produces an intermediate form. PHP’s virtual machine then interprets this intermediate form. PHP’s “generated code” feature allows us to walk through this intermediate form, better understanding exactly what PHP does with the software we write. We’ll begin with a three line example, observing the generated-code changes […]

Memoization is another form of memory use. I see it regularly used for improving application performance, but it’s also used to improve compiler performance. To learn the concept, we’ll use a PHP project with database tables, then look at other ways to use the technique.

Memoization is another form of memory use. I see it regularly used for improving application performance, but it’s also used to improve compiler performance. To learn the concept, we’ll use a PHP project with database tables, then look at other ways to use the technique.

We normally don’t care about abstractions in software, because they exist to hide details we shouldn’t need to care about. However, sometimes, we do need to know the detail. An essential part of how PHP works involves memory management. This month we’ll see new ways to think of memory itself; we’ll also introduce a learning tool we’ll be using in upcoming articles. We’ll be simulating an ancient mainframe computer, and its hard-wired operator console, using modern text messages.

The PHP compiler source code includes many patterns that can be frustrating and intimidating, because they are so different from typical PHP code, until we understand the structure and context. C’s preprocessor has a significant role in these unfamiliar patterns. We look at several of these patterns in the compiler’s PHP Array implementation.

We continue our deep dive into how PHP implements arrays as hash tables. We’ll see how the collision chain works. We’re not ready to dig into the C implementation just yet, so we’ll see how to build and rebuild the hash table using PHP code. This month we’re learning how PHP arrays are stored and […]

We all use PHP; it’s open source, which means anyone can take a look. However, it’s not as easy as with the various PHP frameworks, because PHP is written in C and makes heavy use of C preprocessor macros. We’ll see it’s relatively readable once we know how and where to look.