On Dikiki.net today, there's a new post that's a continuation of a series (first post, second post) dealing with macro programming in PHP.

Without going into theoretical details, some of which are quite alien to me, I'll try to describe some of the challenges that pattern patching rewriting macros might pose for a language like php. After brief explanation what kind of a beast is this, I try to explore some of the finer points, which might cause problems. The intent of this post is to sketch a design and highlight some of the possible issues.

He breaks up the post into a few sections:

• pattern matching rewrite only macros - a bird eye view
• Transformation time
• Basic/skeleton shapes and intermediate shapes
• Code generation issues specific to php
• Hygiene
• A rough macro shape outline
• Output/Status of the project

There are code examples (of how it should work) and explainations of the issues PHP would face to accomplish this goal.