On the SitePoint PHP blog they've posted another tutorial from Christopher Pitt, this time about macros in PHP, and how you can use the Yay library to add in custom pre-processed macros to your code.

I get really excited when developers feel empowered to create new tools, and even new languages with which to solve their problems. You see, many developers come to PHP from other languages. And many PHP developers can code in more than one language. Often there are things in those languages — small syntax sugars — that we appreciate and even miss when we’re building PHP things.

Adding these to a language, at a compiler level, is hard (or is it?). That is unless you built the compiler and/or know how they work. We’re not going to do anything that technical, but we’re still going to be empowered.

He starts off by describing the goal: a simple "range" macro that creates an array and fills it with integers. He helps you get the library installed and shows how to use it to pre-process a file and output the PHP version. He shows how to create the syntax for the macro in the format Yay is expecting for the array_slice shortcut. He also includes handling letting you slice out a portion of an array using the same notation. Finally he shows the resulting code after the pre-processing has happened and the macros have been resolved.